My point is you would need a reset to insert the more mechanical versions of these.Feats, I think, would have eventually reared their ugly heads. Sorcerers, or some other version of a spontaneous caster, would also have appeared at some point. I'm pretty sure there'd have been a music or sound-based Bard show up, fairly early on. Skills were already on their way in during late 2e (and have yet to be done well, three versions later); maneuvers would have appeared as an idea in a Dragon article.
I don't know what you mean by "ability mods for every ability".
We could very well have done without dragonborn, tabaxi, goliaths, and all the other monsters becoming PC-playable species.
Skills weren't in 1e and they were integrated into the gameplay loop in 2e. Feats didn't exist. Maneuvers didn't exist. Different types of rest didn't exist.
- Does a ranger get a bonus to their Woodcraft or Animal Handing NWP compared to a wizard?
- Which level do you get a feat?
- What schedule is Pact Magic, Psionics, or True Naming work?
- How does wildshape work?
- What is an aberration or fey or giant?
- Are you doing a ton of bonuses, a feat sets of bonus categories, or reducing things down to advantage disadvantage?
- Is the fighter just +1 to hit per level but the paladin gets a class feature every level?
- How does balance work if you add feats or skills or full caster bards or wildshape druids?
- Is Challenge rating a thing? Do you have encounter building tools.
- How do you add magic or martial to a monster?
- How do you swap a monsters race if they only are ability adjusts and Charisma doesn't do anything for monsters?
- Are races just static ability score adjusts?