Back in ancient versions we had some interesting mods (precisely this one for 1.4.x) who swapped the models of Villagers into Human/Zombie-like ones.
But in recent versions, except MCA and Optifine (i'll explain below), there isn't any alternative to it.
My idea is basically a mod who only replace the models from these models (Villagers, Witches, Illagers - Vindicator, Evoker, Illusioner and perharps Vexes) to human-like ones, and using some predefined player-like skins to differentiate each mobs. For Testificate-like zombies they could just be disabled from worldgen (for coherence) or simply reused for a standard zombie just with a sightly altered skin (Alex zombie version???? Herobrines? Lost miners?).
The only addition beyond aesthetic could be you being able to er... hire (tame isnt a good term) some villagers, they could basically use Wolf AI to follow the player and be able to be equipped with swords and perharps shields to fight along the player, but this isnt so much important in fact.
This would be a great change to get along the player and zombies, both are human-like entities and can get along with the vanilla feel of the game.
Alex (slim)-like variations for females would be welcome! Maybe replacing (at least the villager) sounds for the classic ouch would be a less important addition.
I mentioned MCA and Optifine (and the current Humans mod) as alternatives, but they didnt quite fit some things to be a good alternative: Humans just add new mobs without touching the testificates, MCA add too much complexity (and the "Send child/villager to mine", at least last time i used it, just randomly spawned items in the villager inventory without actually mining, what i think is a bit cheaty/unfair for survival) and for a while even disabled the vanilla trade sytstem (i think this was fixed but...) and Optifine... i need to say anything?
Anyway thanks a lot if anyone are willing to make that!