Wizard:
-Firebolt is going to get buffed by its own nature as a cantrip at level 5. Cantrips are not supposed to be powerhouses and are more weaker/situational spells that cost nothing to cast, with the exception of Eldritch Blast which also has Invocations that can be added to it, increases its power and versatility but that exception exists to give Warlocks a sort of core ability.

Ranger:
- I am fine with them not being summon-able in combat but I'd argue that Find Familiar for all classes that possess ritual casting (Wizard) or the Ritual Casting feat should be free and not cost a spell slot. This should extend to all "ritual" spells, and perhaps if Larian wanted to they could be resummoned in combat but in that case it would cost a spell slot and an action. Also familiar/companion summons should have ZERO interaction in the concentration of Mage Hand or any other spell that gives a temporary controlled creature.

- I actually agree that creature's jump distance maybe should be modified as right now it calculates off of Strength I think? But if Jump has to be a mechanic, arguably animals should be able to do it better.

- I am not sure if increasing the area of effect would be good or bad, but it might be worth testing.

Fighter:

- Second wind is supposed to be 1d10 + Fighter Level so it will get better on its own.
- I don't have much comment on the other two other than Fighters can be ranged as per their class kit, and it is just as viable and valid as a melee fighter. I am not sure how everything is supposed to react but there are many ways to build a fighter to make them a ranged powerhouse and this does not invalidate ranger in any way. (I actually of the opinion that ranger is the most redundant and weakest class but I would not remove them at all and consider them to still be quite good and can have a lot of fun with them.)

Rogue:
- Rogues have many tools at their disposal to do something like this already and later on there will be many more tools. Also invisibility from your wizard or warlock is enough to cover this for now.

Cleric:
- No. Cleric is mostly balanced right now other than enemies always passing the offensive cantrip spell DC when it shouldn't be that bad. Healing Word is ranged, Cure Wounds is touch. Later on there will be even more healing tools, and if Celestial Warlock ever drops there will be even more ranged healing. Healing right now is fine as is I'd argue, only other combat variables need to be modified, like how you can freely eat in combat or how advantage is handled and how easy it is to get.