Not really. Gorenger was retroactively made the first Sentai, but Battle Fever J was basically just aping Gorenger's style.

And how involved was Marvel, anyway? Battle Fever is kind of unrecognizable from what it was intended to be.
Though technically, yeah, they did have a hand.

Aside from the opinion that I don't think Marvel gives a shit what Toei does with Sentai in Japan, or Saban does with Rangers- I really, really, really doubt we will ever get a team up between a Ranger team and Marvel heroes. That would involve a hell of a lot of companies, and a hell of a lot of people to agree to it. Comics? I could see a one shot if Boom Studios and Saban did something with Marvel. Movies? No. That will not happen. Marvel as a movie studio or even company is too focused on their own characters and their stories to worry about another franchise that Lionsgate is helping. You don't see Luke Skywalker or Rey and Finn helping Captain America or Star Lord, do you?

I really don't see where this mindset of "Marvel owns Toei" or "Marvel started Sentai". They co-helped w what? Battle Fever J and Toku-SpiderMan? Regardless, if Marvel wanted to do something with that, and it somehow affected the way Saban Brands did Power Rangers, I still do not think nothing would change as it is right now.

Why Marvel would be interested in toku ?

Yes Toei basically copied Gorenger in forming Battle Fever J. At least in terms of costumes. The team however is actually influenced by The Avengers with even an intent of including Spider-Man down the line. Plus without Spider-Man there would be no megazords. Yes Gorenger was first but Marvel and Toei's collaboration Battle Fever J is the foundation all modern Super Sentai is based on. Marvel is one of two parents that conceived Super Sentai and Power Rangers. Saban is the step dad.

They have been since the 1970s

I'm just saying that, in terms of the spectrum, Battle Fever leans a lot closer to Gorenger than the original Captain Japan concept Marvel originally intended.

Spidey did pave the way for mecha, but that's more just Leopardon being stupid popular and Toei catching on quickly (Though if Supaidaman is brought back in the next Hero Taisen movie, I'mma scream :lol)

No, without anime like Getter Robo and Mazinger Sentai would have no robo as the entire reason Leopardon exists is because Toei wanted to cash in on the 70s giant robot craze.

If the movie is successful enough to warrant renewed interest from Disney, there's NO WAY IN HELL Lionsgate or Saban would sell the rights. Why would they give up something profitable enough to inspire envy from one of their primary competitors? It's just not logical.

Unless Saban Brands get in bankruptcy someday.

Is this why Saban sold the franchise originally?