I short, you sure may believe chess is no sport. And you sure may say it, as long and as many times you want.
But you need to be aware, that by doing so, you do claim that every and each sports authority around the world is illegitimate and that their judgement over the question "What is a sport?" has no value at all.
And for what I know, it sure may have no consequences at all over your life. As long as you don't engage official sports competition with that mindset, lol.
That's such a bad argument it isn't even an argument. Sporting bodies have a vested interest in claiming as much as they can as sports, so their claims or opinions need not be taken seriously.
In other words, expertise is of no value. Those who have invested their lives in learning something must be presumed to be biased. To avoid such bias, we must canvass the ignorant.
Mayan ball courts 1000 BCE. Early American sport.
https://www.cambridge.org/core/journals/ancient-mesoamerica/article/lidar-analyses-in-the-contiguous-miradorcalakmul-karst-basin-guatemala-an-introduction-to-new-perspectives-on-regional-early-maya-socioeconomic-and-political-organization/31075DFA8ADBAA5E7C7320CA6DB93E5E