Search Engine Optimization is not a rocket science, but newbie’s are not used to Google’s way of doing things especially the way they rank pages within a new website.
I know that a lot of SEO’s recently involved into this business see strange things in SERPs. At least those who started their first blog or site may get confused when open the browser and type website brand name or main keyword, and see that other pages rank higher than their homepage. Then, they get confused.
Yes, it is as clear as day if the website or blog is a brand new. What is the point?
Well your website needs an authority in order to have stable rankings. The homepage is still messed, and maybe with non-related content at the beginning.
At a new site or blog, with very few pages, you do not have a lot of material to tell Google, how to rank your pages and the priority of your pages.
You do not have links pointing to your homepage or they are not indexed yet, so the page that will rank for your desired keyword is the one with at least one more occurrence for that keyword than the homepage. Usually, at the beginning, about page tends to rank high for the main keyword/s and even, I have seen contact page rank higher than index page. If someone inserts more text on about page, include contact, social profiles and repeat main keyword several times, then Google may evaluate that page as most relevant for desired keyword, and will rank higher than the homepage.
It can happen with Services page, but also with individual post, if the post is about your main keyword, and have good Meta title and Meta description.
This is a temporary phase. As soon as the homepage get some authority, several quality links, and social media profile links to the home page, it will boost its ranking above all other pages within a domain.
In addition, when you create a new page or post, you have the very first link pointing to your homepage with brand anchor text, and thus give a value and link juice. Each page has its initial rank and juice that passes to other pages. As much pages or posts you create, the homepage become stronger because a lot of interlinks are pointing to that page and give importance.
On the next crawl you will see that your about page is no more a core pillar of your website.
That privilege now belongs to the homepage.