Those 3 types of firearms sufficed & provided all that was needed, in the gun sense, to satisfy the 2ndA.
The subject under discussion is the kind of weapons that you could "keep" and "bear", and not the distracting introduction of weapons of mass destruction, but since you mention it:
There were no hell fire triggers,
A well tuned lock can provide instant ignition, which is asking a lot from a swinging a piece of rock against a piece of steel to fire your weapon.
no hermetically sealed ammunition,
You had better be very careful to protect your powder and cartridges from moisture if you expect them to survive a three month ocean voyage in usable condition.
no precision fmjs,
A well patched ball can strike a human target at 350 yards.
no brass casings,
Musket cartridges are rolled in paper.
no 10 round clips,
Packed ten to a set in brown paper tied up with string!
no semi autos,
Some guys claim to be able to do four rounds a minute but the best I can do is three.
no dum dums,
They had such things as deliberately mutilated musket balls and musket balls with nails driven through them.
no safe safeties.
I have a hammerstall which prevents accidental striking of the flint and steel, and a half cock notch. You don't want your musket to go off half cocked!
.. their 1790 musket by itself was essentially useless in offensive battle.
Yes, but a 1790 musket doesn't get used by itself as an offensive weapon. It gets used alongside dozens of other 1790 muskets firing together. A Company of soldiers is a shotgun fifty feet wide, throwing lead down range three times a minute. This can be quite offensive - and is the very essence of what it means to be well regulated.
You title your reply "1776 muskets were not assault weapons", then you say "The musket only became an assault weapon once it had a bayonet attached". By 1776 most muskets were equipped with bayonets, so by your own definition they
were assault weapons.