Being innovative is hard these days when everything has been already invented.
With each new game idea, there is a hope that it will stand out, be different than the other games on the market, and there are quite a few ways to achieve that.
Shovel Knight is just as enjoyable as the best Mega Man game, yet the cast of characters in Shovel Knight gives it its own identity.
Cuphead is simple in its run-n-gun approach, but it caught people's eye because of the unique visual style.
While there are plenty of different genres, in each genre games are sharing more similarities than differences. You won't have the same experience while playing Rayman Legends and Celeste, but the core mechanics are the same - A to jump, B to run, to put it bluntly.
Total War: Three Kingdoms and Surviving Mars have little in common when themes are concerned, but they require the same amount of thinking and strategizing to beat them.
So, how do we invent something completely new without relying on previous games? We don't.

There are two best approaches to give the game uniqueness and first one is changing one thing that we are taking for granted.
We got so used to jumping in our Metroidvanias that imagining one without that ability sounds kinda impossible until you play Dandara.
Dandara took that exact idea - it took away the ability of its main character to jump and instead replaced it with exclusive wall jumping, which resulted in a highly original way of playing the game despite being in all too familiar genre, not to mention the critical acclaim.
Another example is Downwell that takes all the rules of a platformer and changes them - instead of moving right to left, you are now falling down. Jumping on enemies heads is still a thing, and collecting diamonds is very much in the vein of Super Mario, but by simply changing one rule, the game became something completely original.

The second approach to make your game original is mixing the genres. I know, it sounds weird to take two already invented things and put them together to get something new, but hear me out.
We are not necessarily talking about the games that are divided into two distinct sections with different gameplay, but more about games that seamlessly blend two genres to work together.
One such example is Yoku's Island Express where Metroidvania is mixed with pinball out of all things. It sounds like it should work, and in the hands of less competent developer it probably wouldn't, but I can tell you first hand it is one of the finest Metroidvanias I've ever played. The pinball sections are ever-present, but they are so well integrated into the game's world it feels very organic.

One of the lesser-known games that mix genres is Serious Sam: The Random Encounter that mixes the shooting chaos of Serious Sam games and calculated approach of JRPGs. Again, it sounds like it simply shouldn't work, but it does. This is not just and RPG with Serious Sam coating, but it is truly a blend of both gameplay styles where you need to choose a weapon to defend yourself with every 5 seconds, or use an item that should help you in defeating the horde of enemies, and when I say horde, I don't mean 3-4 enemies that you usually encounter in RPGs, I'm talking about hundreds of screen-filling enemies.
Puyo Puyo Tetris took a slightly different approach, by taking two incredible puzzlers and mashing them together without changing any rules, and somehow it worked wonderfully. While you can play Puyo Puyo or Tetris modes separately, imagine the fun and chaos of playing both styles on the same screen. I've played it for hours and I still can't tell you the exact reason why it worked, but it did.

There are plenty more examples of inventive games that stand on the shoulders of giants, but the point is that in the times when everything is invented, we should look at that as an advantage and not a hindrance. We have so many examples to choose from, to adapt, to reinvent, to mix and match, so it is safe to say that we will keep getting original titles for a long, long time.