Agree with Trents on multiple points.
Don't get rid of your upgrade path because of a 20-40 euro difference in price up front
That said, a max budget is a max budget. I personally would opt for ramen for a week if it meant I'd get to enjoy a hobby more.
The cpu, when you are able to afford to upgrade, is significantly faster than the lower end models.
That case supports full sized ATX motherboards as well, so you don't have to limit yourself to super tiny motherboards like the one you chose.
I would go for this mobo:
https://www.newegg.com/Product/Product.aspx?Item=N82E16813128980
Reasoning:
4 memory slots, so you can opt for a 4x4 gig setup for a grand total of 16 gigs*the recommended minimum for gaming these days*(Upgrade when budget permits)
Support for kaby lake processors. More efficient, and faster than skylake.
and this processor:
https://www.newegg.com/Product/Product.aspx?Item=N82E16819117743
Pentiums are a step up from celerons, but the igp is significantly improved.
As for the OS, you could get away with a windows-like linux distro, or potentially grab a key from
https://www.kinguin.net/category/19429/windows-10-professional-oem-key/
And just because you can't game YET, does not mean you can't grab a cheap 1050ti or rx460 when budget permits and jump right into it.
I'm not going to lie. I miss the days of old where I had a ultra low end pc that i could upgrade piece by piece. It was satisfying to stride towards an end goal.