If characters in Vagante can jump one block higher than characters in Spelunky can, then at Vagante's base 100% gravity, changing the Gravity value to about 110 to 120 (Maybe even 140 to 150 if you're brave) should do exactly what you want.

In order to edit the gravity, double-click the gravity slider/tab and insert the exact value you'd like-- raising the value will make gravity heavier on the player, while lowering it will make gravity push down lighter on the player.

It should be noted that different gravity values might feel really unnatural for players, so you might play around with it a bit-- try and find precise numbers to get exactly what you want. (: Please also keep in mind that, with heavier gravity values, the threshold for fall damage will increase as well. Good luck!

That worked pretty well, thanks for the advice.

All tiles within the level editor are breakable with bombs, explosions, and certain boss' projectiles/moves, as well as the 'breakablewall' entity; Unfortunately, this isn't something that can be removed, to my knowledge- the only way to make a level unbreakable is by editing it to have the same properties as the intermissions, but doing so would also make players invulnerable to damage, plus a myriad of other side effects.

Technically there 'is' an entity that would allow such things, (it's used in the final boss area to prevent the player from falling to their deaths) but how to actually access it is currently unknown. Sorry about that. ):

When I threw a bomb at the bottom floor of the map, it didn't break. (Also I deleted my comment earlier comment about it after finding out about it, sorry for the confusion.)

No worries about the confusion, I've had it happen many times.

You know, custom levels ARE bugged out constantly for some odd reason-- for example, grapple hooks refuse to work in custom levels-- so maybe it's something you CAN do. If you'd like to make 100% sure, I suggest hosting it online by yourself and seeing if they still won't break-- if not, that's great, but if so, I guess the problem is still persisting. The devs haven't fixed the grapple hook issue (which should only be happening in intermissions) so I'm really not sure. Sorry about that.

It works when I host online as well. Now the only things I need are the regular skeleton enemies and cobwebs, but I don't believe I have access to either those :(