Copying and Pasting an Image

This is just one way. It works even if the website owner has protected the image.

In Safari zoom into the scteen with a few clicks of cmd and + key.

Click cmd+shift+4

Drag the cross hairs to top left of image then click the mousepad with ann additional and drag cross hair to bottom right corner.

Release

That places a screenshot image in the Desktop

In Powerpoint select Insert, Picture from file, go to desktop in Finder and select the screenshot.

If the website has not protected the image then right click on the image and select Save Image.

Then insert into Ppt the same way.