I want to do two things here. First, I want to address each of the below "additions", and then I want to add some of my own:
As we approach Season 2 and meet the TOS Enterprise....sort of, it's a good time to look back at Discovery S1 and consider what it has added to Star Trek lore.
The additions I've noted from Discovery S1 are;
- Giving Spock an adopted human sister
Sarek and Amanda never formally adopted Michael; she is simply their
foster daughter.
- The Mushroom Spore Drive, which is public knowledge. Harry Mudd even knows about it.
As others have already said, the Spore Drive's development isn't "public knowledge".
- The magic Mycelial Network aka the force
How you got an analogy to "the force" out of the Mycelial Network (which is based on an actual astrological theory, I might add), is beyond me.
- Making Section 31 into a more well-known organization within Starfleet
It didn't, and they're not.
- The Klingon War with massive human casualties
Star Trek lore keeps expanding. That's the nature of storytelling.
- Klingons eating their enemies
As already noted, this isn't anything new, but, as was pointed out, the Klingons only ate Georgeiu because they were starving, so we don't actually know with 100% certainty that this is something they do regularly.
Now, some additions:
1) Arne Darvin is not the first Klingon to undergo transformation surgery
2) Mirror Universe Humans have a light sensitivity problem that ends up being cleared up by 2265
3) Sarek didn't speak to Spock for 18 years not because he joined Starfleet, but because of his own personal shame at having robbed Michael - due to Spock's choices - of the opportunity to serve in the Vulcan Expeditionary Force, something she had both earned and wanted