Bouncy second floor bedrooms

So I recently purchased a home built in 1900 with some moderately bouncy floors. I lifted part of it to inspect the joists and it looks like they used 2”x6” joists 20” on center. These all span the rooms 15’.

From my research they are all over spanned by a few feet. Is my only option to add a bunch of new joists in between the existing ones or is there a possibility of bridging them?

And ideas or previous experiences would be nice to hear. Thank you!

https://imgur.com/a/BMuzdsH