If you want specific text on a meme, then yes, you do have to copy it.
But if you find a meme with context already(that you want to keep), then you just paste it as is, and create it as a template.(By uploading it and simply make it as a template)
Or
If you want a specific colored background from Transparent Images, then you have to copy, paste(the transparent image), select your specific color, copy your new image, paste it into the Upload Template, and create as a template.
Or
If you want Text along WITH the specific colored background from the Transparent Image that you have selected, then you have to once again, copy, paste(your Transparent image into the generator), select your color, put your text, copy your new image, remove the original text, then go to upload your new template.