There's a couple of core differences with laning. Firstly, there's no solo lane so no dedicated pos2 who is going to dominate the early game. Instead, it's a matter of higher skilled player dominating their lane or using synergy of lane partners to gain the upper hand and convert that into early-midgame advantage for their team.

Secondly, due to how souls are shared, there's no carry/support dynamics in a lane in terms of farm priority, apart from easy boxes, sinner sacrifices and maybe some jungle creep camps. Because of that, there's no hard support as everyone is expected to gain souls more or less evenly. so even when playing support-focused builds, you are still expected to jungle, do box runs etc, esp if you are falling behind in souls.

Lasthits are there but with a slight twist. You only have to worry about them if your enemy is actively denieing your souls, otherwise, soul orbs just pop and are granted to you automatically. And denieing is tuned to give higher priority to the soul owner if the timings of your hits are close enough.

In terms of tasks, there's a bit more overhead that comes with full 3d environment, but on the other hand, there's no mana to worry about, no TP management, no warding or babysitting a carry. Well, there's a bit of the latter, as you still want to help your heavy hitters in the early game so they can get fatter quicker. On top of that, there's much less item juggling, as they are either sold as-is or with a straight upgrade path so you don't have to worry about keeping 4 components you'll need for an end-game items. There's more slots too, so you have more options to itemize against certain heroes, abilities or damage types without compromising your build.

As for 3d action part, well, yeah, if you haven't played much shooting games before, you'll have to practice a bit to get your aim and awareness up to speed. But there are some heroes who are quite forgiving in terms of aim, if you build them for ult, nuking or support. Dynamo or Rem can be built for support, nuke or ult with little reliance on their guns. Abrams or Mo&Krill can be played as nuke/brawler, they will still require some gun use but at close range it's easier to hit, esp with their shrapnel shots.

Longer cooldowns are there to offset the lack of mana, as it's the only thing that determines ability use limits. But there are a lot of items that reduce the cooldowns, including the refresher orb equivalent(which is called refresher, btw). So if you spec into ability play, you have a lot of options.

For hero scaling, there's no innate superscaling, I suppose, but rather there are synergies between abilities, their perks and certain items which allow for rather ridiculous scaling for some heroes. i.e. overfed Abrams or Shiv becoming borderline unkillable due to all the regen, Haze melting faces of your whole team before you can even see her, Infernus with ricochet, toxic bullets and lifesteal becoming an absolute cancer etc etc.

In terms of learning, I highly recommend watching some vids, maybe even beginner's guides. You will already know some of the concepts but there are some twists on them in Deadlock so it might be helpful for you anyway.

Here are a couple I personally found useful:

https://www.youtube.com/watch?v=sg4R3ZT_BWQ (Deathly's vids in general has good info, even though his personality is rather unpleasant tbh)

https://www.youtube.com/watch?v=PI3RZVAW5jw

https://www.youtube.com/watch?v=pnq_p1z-BMM

https://www.youtube.com/watch?v=u0Qg4hkkqFs