But if the person who designs the logo didn't recognize it as their original, then you can still use it. There are people who want their art to be used even without asking for permission. For example, there is a bitcoin logo like this:
wherein you can freely use in your designs, but other bitcoin logos such as those personally edited should be properly cited and you need permission to use it. My advice is for you to try to use photo editing software to somehow create your own logo on your own design.