You can google is pretty easily. Learning to write cursive develops various brain components as well as fine motor skills. I was skeptical as well but just a brief scan of the research shows significant changes in how children think just by learning to write differently.

https://www.psychologytoday.com/us/blog/the-athletes-way/202010/why-cursive-handwriting-is-good-your-brain

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4274624/

https://www.nytimes.com/roomfordebate/2013/04/30/should-schools-require-children-to-learn-cursive/the-benefits-of-cursive-go-beyond-writing