are your articles coherent around a specific searchable topic worthy of indexing? What sort of up to date niche, I had a site that was ranking that was new for about 3 keywords, and all posts were indexed, now all keywords are gone, but I have only 1 out of 10 posts not indexed, so hopefully they come back. Takes time, just keep at the long view,and good content in your niche, with up to date site,and you'll do well eventually even if you have to just outlast everyone else's site! lol
EDIT: I never submit anything to GSC or indexing, I just let posts get picked up naturally and a couple of my authority sites, are same day less than 5 hrs usually, rest of my slower and newer sites are around 1-7 days