Fix Magento website error after moving servers and updating PHP -- 2

Recently we changed servers. Originally, the settings were set so that the PHP version for our website was 7.2, now it is 7.4 which doesn't seem to be compatible with our Magento website. We believe this is what is causing the error. Website: [login to view URL] Error: Internal Server Error The server encountered an internal error or misconfiguration and was unable to complete your request. Please contact the server administrator at xxxx to inform them of the time this error occurred, and the actions you performed just before this error. More information about this error may be available in the server error log. Additionally, a 500 Internal Server Error error was encountered while trying to use an ErrorDocument to handle the request. --------- I have also attached the error log. We hired someone to started fixing it but didn't complete the project, so the website is currently displaying the folders (screenshot attached) What I'm looking for: We need the website fixed and up and running, ideally by TODAY. With the website up and running, I expect the homepage and all pages to be working, for people to be able to add products to cart, check out, make payment, send enquiries, check their account settings etc all as before the website went down. in the olde server the site was running under php 7.2 and now is under php 7.4 , that might be causing the error