> But of course one can then question why are there exactly N different types of fields, with their specific types of interaction (at least in our universe)?

Even that has a (still unsatisfactory) answer.

Poincaré symmetry imposes constraints on the kinds of fields we can have. Gauge symmetry shows us how they may couple.

There are still some arbitrary selections of the possible permutations that nature has “picked”.

Interesting, but (way out of my depth here) why do these symmetries have to exist?

It would be much more satisfying (not that nature exists to be satisfying) if we could explain our universe starting from some universal constraints on things that must be true of any non-random mechanistic universe, plus some set of (< N) non-forced "it must be A or B" additional constraints, then be able to derive everything known about our universe - fields and symmetries etc - (& ideally predict something unknown) as resulting from some particular selection of those additional constraints.

This seems about as close as we could get to explaining our universe... Basically saying that god flipped a coin marked A and B, and it come down A so here we are. Maybe god kept on flipping sets of coins and created a whole bunch of other universes too, whose physics we could also derive.... and maybe one day visit and confirm.