call top X% of your range and go from there. This hand isn't near having good bluffcatching potential, nor anywhere high up.
So fold

I’d probably use a slightly bigger flop sizing with my range on flop, something like 1/3, and consider checking turn to bluff catch river. Could also two barrel 1/3 completely as an exploit.

But when he lead jams, def think we fold this. Agree with what Jeff said. Here, I’d think about my overall range and the strongest hands in it and then compare that to where I’m at here..... I’ll have A6s in range. 22, 44, JJ, maybe a small amount of 76s, AA etc, so considering I have a lot of boats and trips here, it becomes clear I don’t need to defend 55.... then when we consider further that this is an underbluffed line.

* MOD: Moved to the right forum. *

This weird line is probably value bet of the fish so we call just 6x and higher.
turn I think you need to play more polorized and check back.

This line should be overbluffed by fish on this texture (paired lowcard flop, overcard non Ace River) but the tight Formation (UTG vs BB) and especially the overbet Donk allin is concerning. Against smaller donk I would call.

It is hard to get called by worse Hands on turn - especially against your sizing. So betting trash and 77+ I guess and check back a Hand like this to bluffcatch many rivers (this line will be very overbluffed on this board and Formation). When he checks River on low runout you can valuebet small against his Ax. Or you bet smaller on turn (around halfpot) which I would prefer cause Pool (also fish) are struggling to defend enough. Checking and Bluffcatching or betting halfpot should not make a big difference.

your range have all the overpairs and a lot of weak hands that cbet bluff the flop.
villan has 6x,22.35s but the rest of his range is weak from yours overpairs (Ax, 77-TT, FD, overcards, A2s) so its polar vs bluffcather spot

I am tempted to just check back that turn. Its a shame to get check/raised and have to fold when we have 6 cards that shift equities drastically vs his value range.

Flop bet sizing is way too small. I would bet 1/2 to 3/4 pot on this flop. As played the river is an easy fold against most players at this limit. Given his strange line, I have found that most players at this limit who play a hand like this have a huge hand a very high percentage of the time. Obviously, with his polarizing shove on the river, it is basically a nuts or nothing bet. i would save my hero calls for when you are higher up in your range.