Please make sure that the image you are uploading does not exceed 1 mb size limit.
Please make sure that the image file you are uploading does not have space in the image file name.
Aspect Ratio of Background Image
Using a 1:1 image as a background image for your landing page, or a row is more ideal as it will scale much better across different display devices.
Image for Body Background
An image added as a background to the body of the landing page behaves differently than a landing page background. Please make sure to add image as a landing page background if that is your intended use.
Logo image will be displayed as per the theme settings. You can add image box to the landing page and upload your logo in that box. You can also use image with control to manually adjust the image size.