ME1 is for sure more janky combat wise and if you think that now it was way worse before. They did this thing where it was more an RPG than a cover shooter so bullets had things like hit rating and so on. So even if you had like the cross hard lined up directly on the head the bullet might just swing left because of math in the background. Something I think that was more just a bioware thing in the early 2000s.
As for the bugs I saw some of those too. I also had this one where you jump out the Mako and enemies appear to surround you then I jump in and they are gone then out again and they appear again and so on.
As a major fan of the trilogy and 1 being one I actually like a lot.. here is the important thing to do with a ME1 playthrough. Get a super complete finish to the game with good credits, max level, and as much side content as you can as possible. Because I agree playing though it a TON just isn't so great these days because its age is just shown. But if you get that really badass complete playthrough save you get all the cool little side shit that pops up in ME2 (mostly) and ME3 (a little) that come from it. The comic book starters get you the big points but its the ton of small little side things that appear that make ME2 specifically a bit more enjoyable in my opinion.