Eunice here from Shopify, thanks for posting!
We have apps available in the Shopify App Store that can help you achieve this goal. I've gathered a few of my favorites for you below:
POWR Image Slider & Carousel by POWR.io - With this app, you'll be able to create an image slideshow complete with customer quotes for great social proof, or a product image carousel. This app is free to use for 3 slides only, if you'd like to add more then I recommend choosing one of the paid plans that start from $3.99 USD per month.
Secomapp: Banner Slider by Secomapp - This app supports 40+ different types of sliders, works on all devices beautifully, and even allows you to add videos to your slides! This app does give you more variety but does start from $14.99 USD per month once you are making sales.
Image Gallery + Video - EA by EnormApps - With this app, you're able to create a gallery using 4 different layouts, as well as add alt tags to boost your SEO. This app comes with a free plan too, but if you're looking to add more than 25 images I recommend going with one of their paid plans which start from as little as $1.99 USD per month.
For more ways to boost your SEO, I recommend checking out this handy Shopify help page.
I hope this all helps. If you have any questions please let me know.