Me and my sister used to spend long summer holidays in Calgary with my grandparents. Calgary was great for kids with bikes - quiet suburban roads, cycle paths on all the main roads, and lots of creekside parks with swimming pools and playgrounds. Happy times!
Every time we'd have grown since last time so grandpa would kit us out with new second hand bikes. One year when I was about 12 mine was a 10-speed boy's racer with drop bars. I thought I had the coolest bike in the world! Though the attempt to ride no-handed ended up in major road rash and a much better understanding of the risks of gravel
That was my first proper bike as far as I was concerned, though I have no idea what sort it was. Since I'm only 5'1" now, I think it probably had 24" wheels so really just a kids bike still, but a proper bike to me.