Images do not show in the website, but they appear on new tab

You will need to learn about the Template Hierarchy, which is the process that is used to select the code that ‘builds’ the page. Within the template is the code that will display images, content, etc.

You will also want to learn about “Child Themes“, which is a way of customizing a theme without affecting the theme code. You don’t want to modify the theme’s code because any changes you make will be overwritten by a theme update.

You might also consider contacting the theme’s support forum to ask questions there about your theme. You have already determined the theme is at fault, so the theme’s support is the place to ask questions about theme problems.

So, the template is what needs to be changed. And to do this properly, create a Child Theme and copy your theme’s template in there, and modify that code.