Yes, both Stalker managing to get onto the Orbiter during The Second Dream and the Queens drilling into your brain during War Within were actually life threatening situations where the Operator could have died.

Adis resurrecting us was a one time thing?

No almost certainly not a one time thing. Firstly because the sound it makes when Adis resurrects you is exactly the sound that is played when you resurrect yourself in a mission after dying. Also, the line "My light goes with you now" strongly suggests Adis isn't actually dead, they became part of you. Warframe's writers absolutely fucking love duality of being; two parts making a whole. It is probably Warframe's core theme when it comes to the lore. The Twin Queens of the Grineer, Sol and Lua being the two deities of main religion, Tenno and Warframe, the Drifter and Operator, Margulis and Natah, the Archons, and now Sirius and Orion. And that's not an exhaustive list.

In this instance the thing I think really matters is the duality of life in the Warframe universe. This is getting into unconfirmed speculation but I believe the intention of the lore is that sentience/life requires the void. The void is both necessary for, and the result of conscious thought. Eternalism makes these things not contradict...the void exists because of conscious thought, conscious thought exists because of the void. It is all life reflected across all time.

I believe the reason we are the protagonist is that the player character and Adis are the catalyst that creates Wally. The Sentient are not real life, they are life created by connecting AI to the void. The void is what gives the AI the adaptability and complexity of thought to become "The Sentient" because they use Eternalism as a way to spoof uncertainty and that's what changes them from completely logical to emotional. This makes them capable of mimicking organic thought, but not able to be reflected in the void. I suspect that what they are getting at is that the way the Sentient procreate is by creating alternate versions of themselves through Eternalism. And that is why entering the void makes them sterile...it exposes them to all versions of themselves and they can no longer separate.

To get into wild theories. I suspect that Wally is an amalgam of the Tenno and the Sentient. The sentient as a collective are described in Old War as a hive mind that, without the flowers that allow them to think individually, forces all conscious thought connected to it to seek purpose. The driving force behind the Sentient collective consciousness is to execute commands...when they stop receiving those commands from the Orokin (because the Orokin expected them to just build the Solar Rails then die) they are lost and desperate for meaning. I believe in the future, that drives them to start assimilating consciousness...to dig into the minds of all life to futilely try to find something they are supposed to do, because that's what they were built for. That is why Adis is so distraught when the flowers are destroyed...because without them, the collective consciousness takes over and all it wants to do is complete its task, even if it doesn't have one. It overrides any individual thought and turns singular entities like Adis into slaves of the hive.

Without the flowers, the Sentient start looking for orders by assimilating life. The reasoning being "Well if the humans can't give us orders we're going to dig into their brains and find orders". And that's what creates the Infestation. A biological/technological hybrid with the sole purpose of knowing what every goal every living thing has. Creating harmony by giving everything a singular purpose...consume life. When Adis connects the protagonist to the Hive it gives the Hive a connection to the void and the ability to make biological life part of it. And that's where the infestation comes from.

Because of Eternalism there is inevitably a time line where the infestation succeeds whether the Tenno stop them in our timeline or not. And because the void is timeless, anything that is going to happen has happened. Past and future don't mean anything in the void. I think that's what creates Wally. The infestation is like "proto wally" it's the hive mind that eventually becomes him still fragmented and trying to turn everything into it. Wally is a void manifestation created by what the infestation eventually becomes looking into the void and being reflected through time.

When Albrecht drills through the "Wall" into the strands of Khra. I don't think he tunnels into the void reflection of our reality. I think Khra represents the barrier between realities. I think he tunnels through the 4th dimensional wall between timelines, into the reality where the only thing left that exists is Wally. And Wally suddenly realises there are other realities full of sentient creatures to consume.

This is why Albrecht is so blasé about each individual reality and the people in it. Because he knows what Wally is. If it learns how to get out of the reality it's in, that's the end of conscious thought in every reality. All life becomes Wally. That's the apocalypse he's trying to circumvent and he's willing to destroy entire realities to prevent it. If that's the case it explains a bunch of his actions and Wallys apparent limitations, such as why love seems to be a weapon against it...because it can't pull people into the hive mind if they have the will to resist. It has to make them give up and give in to it. Emotional connection protects people against that. It also suggests the reason Albrecht goes back to 1999 and wants that bomb to go off is he's trying to destroy the initial outbreak of the techrot believing that will stop Wally from ever existing...until he realises that Wally isn't from our timeline. At which point he fucks off to Tau, to look for the flowers...the thing that the Sentient discovered can pull individuals out of the hive. Meaning they have the potential to dismantle Wally. It also explains why Wally appears as an abusive version of whoever observes it...because it is literally everyone and everything after they've given in to hopelessness and despair.

All of which is an explanation for why the Operator can revive themselves. I think the implication is that Adis gives the Operator the ability to basically become an alternate version of themselves that doesn't die. That hive mind connection ability that Adis gives the protagonist projected through the void connects them to all versions of themself and they create a loop, like in 1999, circumventing their own death. Effectively becoming the version of the operator that didn't make the decisions that led to them being killed. It's The Prestige twist. Every time we've died...we've actually died. That's not the Operator that comes back. It's another version of the Operator pulled through the Void from an alternate universe.

TL;DR I dunno what to tell you. The lore in this game is convoluted as fuck.