Washington is a household name as of 2009, Adams is not
Are we talking John Adams, J Q Adams, or Samuel Adams? If it's the last one, I beg to differ.
I have to accuse you of a touch of intellectual snobbery, btw. Most of my friends - not all of whom are nerds, and almost all of whom
are products of
South Carolina public education - would know who John Adams was, and would have at least a caricature understanding of who Attila the Hun was. Calling someone who is large and overbearing "Attila" is actually not uncommon around here - and no, I'm not just saying that for the sake of this argument. I've heard it all my life.
And people of importance frequently continue to have relevance in name, even if the knowledge of the details has mostly gone by the wayside. Most Americans
do know of Sam Adams as a beermaker, even if that's all they know about him. And the intellectuals who bother to find out where the beer's name came from will continue to know the details.
Genseric of Vandals isn't forgotten - or you couldn't have mentioned him.
You're right, though, that some important people have fallen out of the
common knowledge of history - like Genseric. But two things to counter that: 1. The spread of the mechanical press, mass media, and the internet have allowed continuing improvements in the maintenance of human knowledge, and 2. Since the start of recorded history, people always remember the 'biggies'. You know, people who do stuff like die for the sins of mankind, or stop the planet from being blown up by a giant Xindi weapon. (For that matter, it really wouldn't surprise me if some obscure religion
was founded after that happened. If there's a Church of Brady Love - and there
is - I'd have to say Archerism, in the Trek universe, would actually have a firmer basis!

)
And the only place where it's suggested he might have planets named after him is a document read out loud in a mirror universe, originating from yet another mirror universe for all we know.
The other two points about canon that you made - the starship class, and the "Father of the Federation" bits - I'll concede, but while it is
technically possible that the Defiant that ended up in the MU came from a previously unshown universe, I find it highly unlikely that the writers intended for that to be anything other than the Defiant from TOS. One would have to effectively prove a negative to make any other assertion.