There is something really special about European development. Chinese history is absolutely fascinating with a lot of super cool inventions, but nothing stands close to European history and it's power.
You'd need to define that something special, else you sound really racist. More likely Europe stumbled on a couple of things such as reading glasses (that gave much longer working lives to scientists) or the steam engine that gave an advantage.
They don't owe you an explanation just because something they probably said innocently could be construed as having racist undertones. While I'm willing to believe that you believe you are doing the right, anti-racist thing by calling them out, you basically attacked them before knowing what they meant, and that feels more like the bad-faith race-trolling that sometimes pretends to be anti-racism online.
White supremacy is basically this, "we are special". Needs to be called out in its tracks. They don't have to explain, but they can expect push back like I gave and can easily clarify if I was misinterpreting, which they chose not to.
European achievements in the Enlightenment and Rennaissance and Classical Period and Industrial Revolution were special, full stop. You're the racist if you think it's because of their race, as evidenced by you injecting race into the conversation. You see things racially.