Gears reversed (17) after replacing back tire. Why?

It's not possible for the operation of the gears to change just by reinstalling the wheel, so it seems likely that you have just misremembered which way this bike normally operates, which is different to your other bikes.

The derailleur has a strong spring that pulls one way, so the shifter adds cable tension to pull the derailleur sideways, against the spring force. When the shifter releases the cable tension, the spring force returns the derailleur back in the other direction. They come like this from the factory and can not be reversed.

Looking at the photos as you have presented them the harder gears are the lowest numbers and the easy gears are the high numbers, so the derailleur is obviously a 'low-normal' derailleur and has always been. This is different to the majority of derailleurs you'll have experienced before.

I hypothesise that this is not your bike but a child's so your memory of its function is limited and impressionable youngster is not confident in their memory of it either. Or rather, now you have put the idea of it having reversed in their head, they are confidently incorrect.

If it's working then great, successful tyre/tube change. In the photos its not in top gear (1)... If it's not shifting fully into the hardest gear then this would indicate low cable tension (opposite to most DIY guides) or a misalignment of the derailleur, but otherwise functioning normally.