I get you, feeling kinda the same.
- Classes probably will feel more different once we hit higher levels but even considering that, they should be tweaked a little to feel more different at low levels as well, and i agree probably reason they feel samish is because generic actions can be used in a similar manner by all of them (scrolls, jump, shove). also, though it might be just me but i also felt given everybody is able to do the special attacks provided by weapons (pin down for example with bow) that also make every char the samish a little bit? i think these weapon skills are a good idea in general but im not sure if i like that everyone has access to these by default?
- Melee chars indeed could use some variety in actions to keep it more interesting, when in tabletop we play and somebody is a fighter they dont just attack but sometimes do some extra stuff (try to knock down, hold, unarm enemies, even to climb on huge monsters). Again, i know fighter gets more special actions and manouvers like these at higher levels in dnd5e, but maybe there is something they can add? I saw some good ideas shared on this forums already
- about missing. they are working on a loaded dice mode as far as i heard but setting that aside: it would be nice to have more ways to buff attack chance before fights. There is a couple of skills already, i expect potions be another way, i wouldn't mind to see mood factors (after a delicious meal or a good song by the campfire all members receive +1, something like Astarion's happy bonus) and then a better tutorial to explain how these chances can be increased. Maybe there is a lot more ways already im not familiar with, it just needs to be highlighted more by the game
- and again i agree, some battle scenarios also feel the same, besides tweaking the action economy as mentioned earlier they can make interesting and diverse AI behaviours based on the enemy's intelligence so they can either attack in group/attack strongest or weakest char or even downed ones first, try to protect their leader, lure players into a trap, or run to ring the alarm etc. also i think if enemies in later acts could have more vulnerabilites and resistances to bludgeon, piercing, slashing attacks and elements, spells it would also spice things up.

I also agree on almost all of the positive points, though im not a fan of the i can fast travel to anywhere anytime, i see why most people prefer that.
Just my 2 cents, im pretty sure Larian listens to feedback and will make meaningful changes to combat, im looking forward to see how much they are willing to tweak though, i have the feeling that we will find out in the upcoming patches!