The Store Manager Represented Racism

I went to the store shopping with my friend this morning. When we got the waiting line, there was no other customer behind us. One minute later, a man came to before us. Since they don't understand English, we just let them waiting before us. Then my friend look around the clothing near, when I talked to my friend, there was a lady didn't ask me whether I'm on the line or not, directly stood at front of me. When the man was called, it seems he was waiting for somebody, so I told the casher that I'm waiting behind the man. The lady yelled and said she was earlier than me. I responsed that the entry video could show the true who it was the first waiting there. But the store manager who was helping at the custom service asked me to back the waiting line. I felt unfair, but she just ignored me even there was no customs. She totally represnted racism to me!