Was your kickdown linkage connected correctly?
I hate to say it, but if the steel is blued at all, it was slipping and those clutches/steels are probably toast. Any smell of burnt anything indicates something was wrong and is not kaput. Hard to say without a clutch pack clearance measurement, or pictures of anything. But the 'sounds in first gear' and lack of hard shifts are all pointing at a slipping clutch pack.
Again, the forward clutch is engaged in all forward gears and you have no forward gears but do have reverse. Reverse does not use the forward clutch, so something is up with that clutch (it's the one furthest to the rear).
Something could be jammed up, not letting that pack get fluid and thus not engage, but that's a quick air check.
Your filter should stop any larger debris from entering the valve body.