Hi and welcome. I took a look at your listings and had a few thoughts. What you are experiencing is common enough with new sellers that there is a theory that eBay may give new sellers a boost in visibility when they first start listing to help get them established. It is just a theory, but there are several ways to get and maintain good Search placement and to bolster sales.
One thing I noticed overall is a lack of keywords in your titles. For example, take the listing for "Harley Davidson T-Shirt Graceland Memphis Tennessee". What size is it? What color? Is it a Man's or Woman's or Unisex or Child's? Why isn't the word "Elvis" included? Even tho some of this info is in your Item Specifics and Description fields, it also needs to appear in your titles.
A second example is "Lot of 30 Rings" . Are these Costume jewelry or Bubble gum prize or Fine Jewelry? What is the metal color? Are they multiple sizes? What styles? What material--are they Sterling Silver or Pewter or Gold Filled? There is no information about anything, why should I click on it? There's no close up shots. No detailed photos. Just one picture and a 4-word title. No details equals no sales.
The same issue exists with this title: "Lot of 2 Golden Gate Casino". What is it you are selling? From that picture, I can't tell what it is. There are people that collect hotel sewing kits. There are those who collect casino memorabilia. So those keywords need to be included. What era or year is it from? It says Lot of 2, yet there is only one item shown in the pictures. Both items need to be shown, in detail.
You need the shopper to click on your listing thumbnail, and an absence of information can cause your listing to get passed on by. All they get to see initially is the title, price, and picture. Those three things need to entice a viewer into becoming a buyer interested enough in your item to open the listing. Title keywords serve an important purpose in gaining SEO. Below is a link to how to increase traffic to your listings thru Search Engine Optimization. I think you will find it helpful.
eBay gives better search placement to sellers who offer the listing elements that it deems important, its Best Practices. Things like one-day handling, a buyer-friendly return policy, and free shipping can give you a boost in Search results. These terms may not be your cup of tea yet, but at the least, should to be considered when examining one's overall strategy.
Since you are selling tee shirts, make sure to hang them straight on the hanger, against a white or neutral background, nothing else in the shot. Iron or smooth out the wrinkles before photographing so the graphics are clear to see. eBay looks at the quality of the listing, not just quantity. So rather than churning out listings, spend some time on presentation and completeness of information.
You have made a strong start and now your listings need tweaking to be the best they can be. Good luck and wish you much continued success.
https://pages.ebay.com/seller-center/listing-and-marketing/boost-traffic-with-seo.html
