I bought a Canon 550D because everyone kept telling me I would be a great camera for beginners. Afterwards, some others told me that this camera is a bit beyond entry-level, more like mid-range or something, and that I could've gotten an entry-level camera for much less. How come the 550D isn't a real entry-level camera, when it's so far behind the 7D except for the 18 MP?
To be only slightly more fair than necessary to the uninformed, there is a level in Canon's line below the "hundreds" series (or the "i" series in North America). The 1100D (the Digital Rebel T3), and the 1000D (XS) before it, are cheaper and have lower specifications. To those whose experience is limited to big-box and department stores, it may seem like there's a big difference between them, but operationally the difference is very slight. They offer pretty much the same modes and user features; the differences are in image resolution and quality, speed and (most noticeably) price. The "thousands" series is not more beginner-oriented; it's just a way for people on a more constrained budget to get a foot in the door. But both the "thousands" series and the "hundreds" series are entry-level cameras.
Nikon's approach to the same problem (people on a very low budget) was to un-discontinue the D3000 after the better, newer D3100 was introduced rather than to produce a new similar but lower-spec body.
Canon's mid-range camera is the two-digit model (currently the 60D). While it is still rather beginner-friendly when the beginner is interested in learning photography, it does have a few extra buttons and dials that people who just want to step up to a "better point-and-shoot" might find intimidating. Those extra controls mean fewer visits to the menu screen to change settings, but there are still beginner-friendly scene settings and so on to help beginners get the pictures they need to get before they've learned how to do it themselves.
Single digits other than 1 indicate advanced-level cameras. Again, there are more controls to use without going through menus, but the hand-holding for beginners stops at this level. Sure, there are still all-automatic settings, but now you have to go digging through the menus to make the camera do all of the work for you, so the positions relative to entry-level and mid-level cameras are reversed.
Canon has always reserved the number 1 for its full-on professional line of cameras. They're expensive, rugged, and in a lot of ways actually simpler than the entry-level bodies for someone who knows what they're doing (or wants to learn how to do everything with minimal assistance from the machine). But they won't out-guess you or try to figure out what you're doing, so using them effectively means a lot more than charging up the battery and installing a memory card if you've never used an SLR before.
Difficult to say, and I know Canon class it as entry level, because the 50D/60D would be their mid-range... However below the xxxD series, there is the xxxxD series -- the 1100D for example. VERY much a beginners DSLR.
Honestly - your 550D is a great camera. Don't worry about it and just get out there and take pictures and enjoy it!
Had you gotten the 1100D you would most likely become frustrated with it as your photographic skills progress. Your 550D will provide you with years of good service and allow you the freedom to stretch your photographic wings.
As far as Canon DSLRs go, it is entry level. The 550D and 600D are entry-level. 50-D is mid-range. 7D & 5D "prosumer" and 1D professional.
Some people wouldn't consider a DSLR appropriate for a true beginner to get started in photography. I'm sure they meant you could have started with a compact camera for instance.