few things I can think of...
- too little content
- your content is not qualitative enough, or it's duplicate / similar to the content of other sites ranking in top 10, so google has no use of it
- your site is not mobile friendly (I've heard that non-mobile friendly websites don't get indexed anymore, not sure if it's true but if it is, it's a big deal)
- your content pages might be tagged with "noindex" tag either by one of your plugins, or by the htaccess / robots.txt files
- you've not submitted your sitemap to GSC and - while this is not mandatory for a site to be successful - it can still help (especially newbies) to find their way around SEO by following google's tips
Last but not least, it's also possible that not even your homepage is indexed but you can see it because you're logged into your google account (gmail, Youtube, etc) and google shows you what you want to see, or what you own. This has happened a lot of times for me in the past, so to check whether or not any of your pages are really indexed your best bet is to (preferably log out of your google account first and then...) copy-paste each URL, manually, into google between quotes (the quotes are important, so don't skip this) and hit "enter"
If you do this and you can't even see the homepage indexed anymore it's clear as day that google hasn't indexed any page from your website for whichever reason (fresh new site and google have not had time / possibility to discover it yet, your domain might be penalized / blacklisted / flagged by google in some way and now google refuses to index it, your pages could be blocked from being indexed by some of your plugins - usually the SEO plugins do this, etc)
It's hard to say the exact reasons without knowing your site and doing multiple checks, but it's probably one of these...
My recommendation is to create a sitemap and submit it to GSC and give it some time (up to 7 days, but you can check multiple times per day if you want, sometimes it's a matter of hours anyway) for google to discover all of your content via the sitemap and index all / some of it if they find it useful.
Even if you don't get indexed, when you submit the sitemap to GSC google will usually tell you why it can't index the pages, so it's worth submitting the sitemap.
As a last resort (and since you only have a handful of pages), you can use the "request indexing" feature inside of your GSC, for each URL separately. Again, if the content is good and the pages are not blocked by "noindex" tags one way or another, requesting indexation manually should work...
If it still doesn't work even after manually requesting it... well, I don't know in this case, but it's probably either bad content (usually 100%, unedited AI content tends to not get indexed), or your site is not mobile friendly like I said, and this can actually impact indexation, or - worst case scenario - you've bought a bad expired domain that you thought was good because you didn't know how to check it for red flags, and now you suffer the consequences...
