Person schema helps Google understand your expertise, and identify the other channels you are writing for or managing.
Person schema is a good way to support E-E-A-T “Experience, Expertise, Authoritativeness and Trustworthiness” of your content. Person schema may also help you trigger a Knowledge Panel in search results, or control what it includes. Using schema is not the only signal Google considers when deciding which brand-driven searches need to trigger a Knowledge Panel but it may be a contributing factor.
Being included in the knowledge graph also means appearing in related searches (and potentially SGE answers).
This helps Google in several ways:
Overall, structured data allows Google to better grasp the E-E-A-T of pages, sites, and entities by clarifying relationships and providing extra entity information. This improves Google's knowledge graph and ultimately helps them provide higher quality search results.
Implementing structured data is beneficial for SEO when done properly, as it helps Google understand and represent your content more accurately.