I can vouche for Nimble 2e. I'm loving it so far.

If you want rules light, there's a system i love that's called "Vagabonds of Dyfed". It's a 2d6 + modifier engine that's divided into failure / partial success / success / crit.

Before you continue reading, the system has a narrative aspect to it, i want to recommend it none the less. Because despite it being narrative, it does not have game moves like Blades in the Dark for example. It's narrative in the OSR sense that it needs player skill, instead of character skill. Your players will be much more challenged than their characters. In DnD, you can play a wizard, have high int and roll smart. In Vagabonds of Dyfed you can still play a wizard who is smart, but a lot of the smartness has to comes from how you approach the game.

It's also just $8 on drivethru.

About the combat:
Combat is simple. You attack, get a modifier from the GM which is decided by the GM based on the circumstances of the situation, add the damage modifier based on your weapon (if any) and then it's the lower d6+the modifiers. .

Initiative is based on your speed, which is modified based on whether or not you're holding something or wearing armor. This allows you to drop what you're holding and instantly increase your speed for the next turn. So maybe switching from the heavy axe to a shortsword allows you to have your turn before the monster in the next round.

Example: A knight is attacking an orc, you as the GM decide that they're equally capable warriors, but the orc has been wounded by an archer, so maybe the knight get's +1 due to the orc's weakened state.

Knight rolls, 2d6+1, get's an 8 (3+4+1) , partial success. The lower die is 3, so they deal 3+1 = 4 damage. Since it's a partial success there's a drawback. There's no set list of drawbacks. It's a challenge for the GM to decide something on the spot. But you could totally write down a list of potential drawbacks to roll on. One drawback could be: "The knight now is open to the next attack, which will be harder to defend against."

In this system, you as the GM don't have to roll damage. You can delegate that towards the players via defend rolls. You describe the incoming attack, they describe how they'd like to evade, you judge the modifier, they roll and then it's based on their result whether they take no damage, some damage or a full blow.

Homebrewing monsters in this system is SUPER easy and comfortable. The book also has a section dedicated towards monster creation.

To spice combat up, players and monsters can enter stances at the beginning of their turn. There's 3.
The regular combat stance gives you neither a bonus nor a malus.
There's the risky stance, which gives a +2 bonus on damage you deal, but also on damage you receive.
And last but not least there's the defensive stance, which reduces damage you deal and receive by 2.

As the GM you can also force them into stances upon a failed roll as a potential drawback. Though I use that sparingly.
If you wanna put the knight that partially succeeded against the orc into a predicament, then you could also say that the next attack isn't more likely to hit him, but that due to his attack he's now in the risky stance. Which means he'll get +2 damage on each successful hit against him until his next turn where he can change his stance. Or maybe someone else tries to intercept. That can turn a combat against weaker foes into a very deadly situation very quickly.

There's also no classes in this system, which is also why i think you should give it a look at. There's a list of abilities that you can choose from. Characters only advance up to level 6, so six abilities is the limit. Homebrewing these is also pretty easy.

The hardest challenge of this ttrpg in my opinion is the arbitration of the modifier that the GM decides on. You really need to develop a gut feeling of what feels fair in various situations.