There is a possibility that git is automatically initialized within your react project directory. Which means a .git folder is created, maybe that is the reason it cannot do drag and drop. This issue can be fixed by either delete the .git and again initialize using git init then you can add and commit your directory content. After that you should set the branch and add the remote repository using git remote add origin <repository-url> .
If there is any error i made or if there is any other useful method of doing so please let me know. Today is my first day in this platform and i would absolutely love to learn new things.
Thank you.