The Marvel Rival Devs played it too safe with both new characters in Season 1
Invisible Woman
Currently sitting at a 47.79% win rate across all ranks. Many content creators initially put her in "S Tier" and said that she is a "high elo" support. Yet in Diamond+, her win rate actually goes down to 47.61% and is the second worst support in terms of win rate after Jeff. Even the "people are still learning her" argument doesn't really hold, as her win rate actually went down in the last week.
Mister Fantastic
A much healthier win rate across all ranks at 52.15%, but the problem is that he is niche at ~6% pick rate (you probably don't see him very often). Niche heroes naturally tend to have higher win rates as they tend to have a dedicated playerbase. In Diamond +, his pick rate goes all the way down to ~4% and his win rate also falls off.
I do think NetEase were probably playing it a bit too safe for S1, but having your new heroes in this state is not the play in your first seasons. This is the most crucial time to build more hype and try to grow your game. If the game was already out for 2 years and the new heroes released in this state, I think that would be more acceptable.