Better to send backlinks to home page or blog posts?

You are saying you just started 15 days ago. So wait for two more weeks at least. Your site is very new for building backlinks. Concentrate on creating content for now and then after a month you can building backlinks slowly and gradually increase the backlink count!
You can use backlinks for both home page and inner page. Ask the seller to make 2 links per post one for your home page and another one for your inner page. Most of them will accept 2 links per post. If they are not accepting you can use some backlinks for home page and some for inner page

Whenever I build links for my clients, I don't point all the links to the home page as Google might consider that as spam. You just need to appear natural in the eyes of Google to play it safe. That is all.

You can build links to both the homepage and inner pages by focusing on brand keywords for the homepage and secondary/variation keywords for the inner pages. As mentioned above, when building links, aim for 2 links per post: one to your main page and one to the relevant inner pages.

Before starting the link-building process, make sure your website and its pages are properly optimized (On-page SEO).

Mixed of focus is workout here. Do strong backlink building on both home page and your blog posts.

At the start, build backlinks to the root domain - afterward, create links to the best-behaving post on your blog

sending too many links to the home page if it does not make sense is also a foot print. it is better to distribute your link profile to the entire site structure.

you can build backlinks from a variety of sources to avoid looking spammy.

In my experience, it’s better to send backlinks to both, but with a strategy in mind. Sending backlinks to your homepage can help build overall domain authority, but linking to specific blog posts can boost their ranking for targeted keywords.

As you said a mix definitely works the best! Homepage links for general authority, and Blog post links for ranking individual pieces of content. You would also have to play around to find what works best. It’s about finding the right balance based on your goals!

Target the articles with the high value keywords so you can have the strong engagement and it can highly benefit from backlinks.
Home pages acts as a main entry point and without links pointing to specific pages the link distribution might not that much effective.

I recommend mix backlinks. Make sure it's relevant to your post.

Start building links at the homepage at the start then start slowly building to inner pages you want to rank…

Do both the homepage and the blog post, and make sure they are relevant