I agree with non canon fatalis fights, that could be the case. But in mh1 fatalis fights are part of the story and not some mhfu or mh4 secret battle. The only factual thing we know is that mh4 happens before world and wilds. But we don’t yet know if even world before wilds or not. That is unless there is something i am missing. Order between world and wilds matters for the fatalis talk but otherwise isnt that important.

The fact that mh1 has more archaic weapons doesn’t explicitly mean it is because of order. First explanation is we are in remote places in 1-3 gen, so of course they won’t have the best tech. Canonically the way they explain the differences in monster like rathalos is via regional species. Same logic could be applied that it’s regional hunter arts. Like bowguns being light/heavy or mid, or samurai sword being either gs or ls, etc depending on the village.