Always a fun thought exercise, even if it does seem suspiciously similar to a previous thread
If the goal was to create a genuine competitor to 5e, I think these sorts of decisions would need to be informed by market research. But I have no interest in that and am going to ignore that part of the premise.
D&D 5e has always underdelivered on low magic and sword and sorcery (not the same thing, but both difficult/absent), so I would try playing into those character types.
Classes:
- Alchemist--an intelligent and/or charismatic class that creates cures, buffing elixirs, poisons, propellants, etc. it would not be explicitly magical, but some subclasses would lean that way, it could encompass a scholar-adventurers, witch hunters, transmuters, and maybe illusionists (1/3 caster)
- Barbarian--not the same one as 5e; themed around brute force fighting and wilderness survival--rage would not be the central feature. Archetypes like beastmaster and hunter could live here along with berserker
- Knave--skill-monkey and agile fighter with lots of tricks, could lean towards swashbuckling, sneakthievery, dabbling in the occult (1/3 caster), or tactical battlemaster/warlord archetypes
- Sorcerer--using this more evocative name, but designed more like a warlock--would start out NOT having signed a pact, and finding a supernatural patron would be a major goal. A lot of it's casting would be built around rituals. Pacts would include lords of chaos, lords of law, and stranger types of things.
- Warrior-Monk--I'm a bit on the fence about what would be included / differ from 5e.
- Tiefling--the majority group in the dominant civilization ruling the major cities as dens if iniquity
- Serpentman--as above, but in decline
- Lizardman
- Goliath
- Thri-kreen (or green martian)
- Birdperson
- Changeling
