I will try and explain a few things for your understanding. Hopefully I will clarify how links and header tags are handled by search engines and how they relate.
When a search engine sees a link, it follows it. When a page is fetched, all links found within the page are entered into the link index. Each link has at least a from (source) page and a to (target) page along with the alt text. Also consider that analysis of the link is also stored including where on the page the link is found (template versus content), where in content, analysis of the link, analysis of the content block or portions of the content block if found in content, etc. If only one end of the link is confirmed, the source page, then the link is a dangling link. Once the target page of the link is fetched, then both ends of the link are confirmed and the link is no longer a dangling link. It is possible that the target page does not resolve and returns a 404 or a 410 error making the link a broken link. In this case, the link remains in the index and is marked as broken and likely the error code is stored too allowing a 404 to be retried.
Historically, a search engine who fetches
www.example.com/posters/red-posters/ will not fetch
www.example.com/posters/. Why? Because
www.example.com/posters/ may not have a page. It could simply be a folder within the path. For
www.example.com/posters/ to be fetched, there must be a link to that page. WordPress is good at creating these pages and links to these pages and making them valuable. However, not all sites or CMS do this.
A few other considerations I will throw in for completeness. Where the links are found within the hierarchy of the navigation and other pages. Links found on the home page are more important than links found one click away which are more important that links found two clicks away. Links are evaluated both between sites and on sites using a trust network model where hops (clicks) and values between hops are taken into account. The second consideration is SERP performance. A SERP link can perform better than another which adds value. Sometimes this does not appear to make sense except that the title tag and description meta-tag used in the SERP link are more compelling. This changes over time as search changes. Keep these in mind.
Having said that, the link is evaluated however it is taken as a whole as a link. For example, for
www.example.com/posters/red-posters/ will not insert
www.example.com/posters/ into the link index without a link. However, the semantic evaluation of the link will break the link into elements. For example, the domain name, the path, any file name, etc. A domain name has more value, though slight, than the path which has more value than the file name and so forth. Think of this in terms of reading from left to right. The path will be broken into semantic clusters using the / character. Each semantic cluster from left to right will also have more value. This means that
/posters/ has more value than
/red-posters/. Again, this is only a slight gain in value. Each element of the URL and semantic cluster from the path will be evaluated for meaning. For a path, it is natural that the left most cluster is topically broader than the one to its right which is topically broader than the cluster to its right. From left to right, each cluster becomes more specific topically. This is how people think and also how people enter search queries. I say this so that you understand how links are evaluated for meaning which is different from how a link is followed and stored as a link.
Next, please understand that the headline read order remains. This includes the link to the page, the page title tag, the h1 tag, and other elements are evaluated to understand the page topic. While there is more to the headline read order, think primarily in terms of these three elements working together in the order I have given them. This means that the semantic value of the links to a page have more value than the pages title tag and h1 tag, etc. assuming that the link values are strong. This is why my advice to create in content links that are full sentences or nearly full sentences is important. Any link text of one or two words has less value than ones that offer a subject, predicate, and object that allows better semantic understanding. Strong links along with strong title tags along with strong h1 header tags offer more value that most people realize. Please keep in mind that the SEPRs will match content and not header tags. However, header tags are required for semantic value in analysis and remain important in that respect. This leads to the notion that header tags are not important for search, however, they are in that they give semantic value to the pages topical scores. They are still important. That said, semantic values of any link to a page along with the semantic value of a title tag and header tag should be complete and complimentary.
In your case, the appropriate semantic cluster found within the path equaling the h1 tag, and assuming also the title tag, even though not fully semantic with subject, predicate, and object, should compliment each other just fine and give a good understanding of what the page is offering. For e-commerce sites it is not expected that all elements be fully semantic so your example makes sense. Clear as mud?