Great. I find a cool way in which the prequels screwed up and then you guys want to defend the bloody prequels. Sometimes I just don't get people.
Judging by what we see onscreen, kid clones must be cloned off Boba and adult ones off Jango. And if there's a third clone actor (I didn't notice) there must be a third clone template (another son of Jango?). So yeah the clone army is based on more than one guy and the Kaminoans failed to mention it.
Presumably the Jango clones were done earlier and later the Kaminoans moved on to cloning Boba, hence the older ones looking like Jango and the younger ones looking like Boba. Also, the Kaminoans are both a bit shifty (they pretend they're all cloned from one guy) and maybe a bit dumb (they think they can pass off all the clones as one guy) or maybe human faces just look all the same to them so they think they'll look the same to Kenobi. The shiftiness may be down to having an alien mentality with possibly a different moral system and different values and modes of behavior. Kenobi doesn't comment on the kid clones being different from the adult ones. Maybe he's just being polite. Kenobi is a polite sort of guy. Maybe he's being underhanded in his own way. That's in character too.
There are undoubtably many plausible explanations for this stuff. You have to stretch far less to explain it my way then you have to to explain Boba clearly not looking like a clone of Jango.
Luke and Leia are hardly a similar situation to the Fett situation. There's no obvious onscreen proof that they're not siblings. There is obvious onscreen proof that Boba isn't Jango's clone. So with Jango and Boba it's a screw up, but with Luke and Leia there's no screw up. No need for DNA proof. Silly comparisons don't get us anywhere.
Yes, people can change a lot in appearance between childhood and adulthood, but usually only so far. The adult face is a version of the child face and vice versa. Logan and Morrison's faces are not versions of each other.
As regards Jake Lloyd Anakin and Hayden Christensen Anakin, no that's not the same situation as the two Fetts. It's never a great situation when you have two actors playing the same character at different ages. It always stretches suspension of disbelief. But as long as you don't have them both on the screen at the same time and in the same part of the story then it can be just about tolerated. Not so when you have them side by side. Then suspension of disbelief is stretched past toleration.
And C3PX, if you paid attention to what I said, you'd see that in my thinking there's hardly any need for Lucas to clone Temuera Morrison to get somebody to play Boba. I pointed out that Lucas could have concealed the face of the kid or could have gotten a kid who actually looked like Morrison.
Another thing he could have done is drop this whole stupid Boba-is-a-clone-of-suddenly-invented-Jango. All the above has to be taken in the context of the Boba-clone-of-Jango thing being a revolutionary take on a longstanding character, a take that likely doesn't have a solid foundation in the old backstory. If Lucas wants us to buy his bullshit it's up to him to make it believable.