What is SEO and is SEO worth it
Shortest answer, no.
SEO is Search Engine Optimization which is a fancy way to say it's a whole ton of work to get your site to the top of the search engines results page. Which most large companies do by spending a whole lot of money because the best SEO is always changing because the rule that the search engines use are also changing "so that scammers can't take advantage of the algorithm" but it also hurt everyone that isn't a scammer.
Have you seen the complaints about Pay To Be Seen because this is a part of that in a way.
SEO requires all the information you could possible have about everything attached to everything that you post online. To catch it's attention you would need to...
-Have the name of your image have all of your item & your sites info.
-Have a description of your image with all of your item & your sites info, but not quite the exact same as how it is for the photos file name.
-Have all of your item & your sites info as the description for the body of the post/initial listing for your item, but not quite the exact same as how it is for the photos file name or as the caption for the photo.
-relevant labels & search Descriptions for your posts.
-Talk about your item in a post, but not quite the exact same as how it is for the photos file name or as the caption for the photo or the initial post/listing of your item.
-???
-Profit
Or something to that effect. The list of things you will need to keep in mind if you do decide to play with the SEO are...
-Items Photo
-Caption for Items Photo
-Initial post/listing of your item
-labels & search Descriptions for your posts
-Any additional posts about what you do or post or list.
If things are still as crazy as they sound then going back and re-working the SEO on established pages is NOT what you want to do.
However if you do want to play with the current SEO then you would want to read up on it and then use that for a few posts that you will be making in a short time frame. Like for posts about items that are coming soon. This would give some fresh meat to the grinder data to the search engines.
Again, because of how fast and how much the SEO changes I will not be talking about the details here. The rare exception with be if something stands out or if there is something relevant to another area like labels ext.
But everything will change, probably not as fast as it did around 2008-ish but it is ever changing because companies want to pay as little as possible for people who understand the system. Also 'scammers' but that is... really not as good as an excuse these days.
Good luck.