I am not sure about it if Webflow’s Legacy Interactions could help you here, but it never hurts to try. Setup a ‘Load’-trigger for the images and enable ‘Wait for assets to load’ (of course add the initial state and trigger state).
For lazyload, you can try this topic:
Regarding the responsive images:
Try uploading bigger image files anywhere in your page to see if Webflow is creating your responsive images, because I can’t see it in your demo site.
Ps. I would suggest to use a load trigger on your scroll icon, when you load your page now it immediately attracts your attention and you’re missing out on the logo animation. Try to hide the scroll icon first and display it after the logo animation is finished.