As far as I understand in Imperial China lots of disparate people were brought into the ‘Han’ fold for political nation-building reasons. Cantonese and Dongbeiren are very different, but they’re both ‘Han’ for example. The PRC on the other hand seems quite keen on officially differentiating distinct official ethnic groups, but I guess it’s possible that old “inclusive” ideas are still around in niche corners.

You’re not wrong on everyone being firmly included under the banner of ‘Chinese’ though either way.