When I open the file, I can see that you are in Material Preview mode. Material Preview mode gives you a preview but don't take your world and light setups into account, so the render won't look like what you currently see, you'd better switch to Rendered Preview to have a better idea of what you'll see as final result.
Also in the Render panel > Color Management > View Transform, you're in Filmic mode, it will make a rather pale render, switch to another mode, like Standard, if you want something closer to your original picture, unless you have good reasons to be in Filmic, of course.
At last, in Rendered Preview mode, you'll find that your image is still rather pale, it's because your sun has a Strength value of only 1. You can either increase it up to about 4, or plug your Image Texture into an Emission node, and mix it with a Transparent node (maybe it's possible to use the Emission of the Principled BSDF but anyway my setup works). With Emission, your image in the 3D scene will look exactly as it is: