Yeah, I know that, but at what point prior to TAS did GR claim April was the first Captain of the Enterprise?
Probably not prior to TAS, but certainly during the writing of "The Counter-Clock Incident", so that's gotta count for something.
Within the actual show itself (1966-1969) never. 'Captain Robert April' was the name of the Star Trek starship captain in his very first draft of the 'Star Trek' series proposal to NBC (before a full pilot script had been written). Also, in that version the 'hero ship' was NOT the 'USS Enterprise'; it was the 'USS Yorktown'.
There is no question but that Gene Roddenberry was IN CONTROL of the animated show, every bit as much as he was in control of the original live-action show.
Yes, there were outside influences in TAS, but no more so than in TOS. Yes, there were compromises in TAS, but (again) no more so than in TOS.
I view TAS very much in the same light as I view episodes like "The Apple" and even "Spock's Brain." That is... they're "dramatizations of real events" which may have been subtly different in the "real Star Trek universe."
The worst elements of TAS were due to the shortened nature of the storytelling, the "dumbing down" of some small elements to meet "kid fare" standards, and the animation shortcuts which had to be used (which necessitated, for instance, the "life support belts" in lieu of actual space suits... allowing the same basic pre-drawn body parts to be reused for animation).
The best elements were the... well, honestly, the more "hardcore sci-fi" storytelling often used, and the more imaginative design (both of which were limited by live-action filming in the 1960s). Today, you could accomplish BOTH through the use of CGI... but that was not an option at the time.
TAS is "real" but not "entirely real" within the "real Star Trek universe," in my opinion.
It was RODDENBERRY, during TAS, who approved the name April as being the first captain of the Enterprise. He may have eventually decided he was embarassed by having done a "kiddie show" (which is really wasn't!) and tried to deny having made it, but he DID MAKE IT, and it was actually pretty good... better, overall, than much of the stuff that came along later!
April was the first captain of the Enterprise. That's canon.
Pike came after April. We don't know if there was anyone else in between.
Kirk took command of the Enterprise after Pike. It's implied, but not 100% stated, that Pike handed the Enterprise over to Kirk directly. We know that Kirk kept the Enterprise for AT LEAST five years. Some would argue it was ten or more. (That would be, a separate mission prior to the five-year-mission, during WNMHGB, prior to a major refit, and possibly a second five-year-mission, to account for all the novels and so forth!)
We know that Kirk handed over Enterprise for refitting and Decker became captain.
We don't know if Kirk commanded Enterprise for any real time after Decker, though it's sort of implied. All we know for sure is that the next time we see her, Spock is in command, and she's a training vessel. It's entirely possible that there could have been another captain in between, who we've never heard of.
We know that Kirk eventually commanded the 1701-A for some unknown number of years, and that she was retired at some point after ST-VI (though it's not KNOWN that it was immediately afterwards).
That's all that we really know.
There's no reason to assume that what we're seeing in the preview trailer is the Enterprise as originally built... or that we're even seeing "our universe's" Enterprise. It could be during the "refit" prior to the second five-year-mission, for instance. It could be the "battleship Enterprise" we've heard hints of. It could be purely figurative and not be the "real" production model at all.
We just don't know. Well, SOME of us know, but those people just aren't gonna say... nor should they!