Don't forget your endgame. Are you using facebook to become an influencer or to promote your book?
Influencers care about engagement such as comments and likes. Promotion on the other hand mainly cares about getting the word out there. Meaning you only care about views.
There's a reason youtube and facebook don't pay for likes and instead they pay for views/amount of time you watch a video.
Getting engagement does increase your chances on appearing on the algorythm. So you should care about it to a certain extent but you shouldn't forget the end goal of your facebook account.
Cherry pretty much mentioned everything else that needed to be said (how writers operate more like influencers and such).
P.S. Engagement with posts/videos is very small compared to amount of views. That's why there are videos with 3M views but only 30k likes. And many less comments.