I took another look at this and it is not so simple.
Don't get how the SB folded getting 7:1
Pre I think call is fine as it is the type of hand that does well multi-way.
On the flop 40 into 105 is strange as it is not big enough to fold out draws. JJ TT would not just limp pre. BB likely hit a pair. If UTG had a J they should have raised. So they could have a T or a 3 or two overs.
On the flop you have 15 outs. OK they could be on AK that kills the Q or a bigger flush but that is poker. 88, 99, or 89 run outs are probably winners so take it as 16 outs. You are 57% to win. Even with 15 outs you are 54%. Since the pot is small I am OK with flatting here. Not really worth raising here to try and pick up a small pot. If you do get called then they might slow down and if you hit you want them betting into you.
You are only behind on the flop to a shove if one has a set, KQ, or two bigger spades. If both have a pair and an over with one spade you are still 47% which is probably the worse you are looking at.
Turn not likely the 4 hit either one. BB of 1/3 still seems like a pair. Again should be charging more to price out draws. UTG could still be on a T, 3, or two overs.
Turn you still have 15 outs. You are are only a 2:1 dog getting 5:1. You are getting over twice the odds you need to call. You cannot fold here.
Yes you are on a stack size that if you raise you need to jam. If you bet 300 they are getting 3:1 and that is 1/3 your stack. So you are in a situation of a big over bet the pot.
If you jam you are going to fold out most hands they hold and pick up a nice 375. A problem with a jam is you cannot have JJ, TT, 33, or JT so it looks like semi bluff draw. JJ and TT would reaised pre and all 4 should have raised that flop to protect from draws. OK maybe you spiked a set of fours on the turn. If they think about it AJ, KJ, and QJ should call and you have no blockers. A T with 2 spades might call. AT spades and KQ spades will call. Yes you will fold out any weaker hands but you are putting 900 at risk and it is not a slam dunk you will get a fold and your draws are good. If you had KQ spades it would be different as you block some hands that might call and your draws are good other than Ax spades.
It is a cheap call. I think just call here rather than put my whole stack at risk. Based on small bets they are not putting you on a draw so you might get paid off. You have position.
A queen or a spade on the river you need to fold to a jam. A call also protects you from better draws. I don't see them bluffing the river.