Selection bias!Most movies and depictions of people in medieval or fantasy eras are quite drab and colorless. As far as we can tell though, that's not how people actually dressed though. Bright colors were the rule for most people. Outfits we would consider quite flamboyant today were quite common as a display of wealth.
So I don't consider most of the images out of line.
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No but really, I was curious so here y'all go:
Generally, the colours available to the lower/working class were dyes obtainable locally from plants without a lot of additional preparation, along with the colours generally found in sheep (wool being the predominant fibre for outer clothing for most people.)
So these would include the wide variety of plants that produce yellows and oranges (such as weld, dyer's broom, etc.), and browns (walnut being a fairly well-known one). Blue was produced from woad and can be processed using urine, which is, of course, available everywhere. Weld and woad can be combined in a two-step process to produce green. Red was a little trickier; madder (produced from a root) is fairly common (basic madder red is often known as Turkey red) but intense shades took more processing.
I also mention in the reply above that dyebaths were often used for several rounds of dyeing, with the most costly articles dyed in the first round and less costly ones dyed in subsequent "dips" (known as exhaust baths), leading to the phenomenon of more muted shades being associated with lower-class items.
One of the reasons reds and purples are associated with the upper classes and royalty is that the dyestuffs which produce the most intense, light-fast results were extremely costly. These include murex (Tyrian or Imperial purple--actually, more of a reddish wine colour, extracted from a type of mollusk), cochineal (ground-up insects), brazilwood, and, by the 16th century, logwood (blues, purples, reds, and eventually, black). There is also alkanet, which is widely available but not water soluble, so it needs special preparation before being used, and produces lavenders and purples that are not quite as light fast as some of these other dyes. Madder can also be used in more complex dyebaths with mordants and with tweaks to pH to produce very deep shades of red, including crimson. True black was a difficult shade to obtain, although deep browns and greys were more common. One of the most common processes involved a multi-step process involving dyeing first with woad, and then overdying with madder. I mentioned logwood above--this is a New World dyestuff and is responsible for the black dyes that became associated with Spanish clothing first, and produced something approaching a "true black" that was colourfast and didn't degrade the fabric as some other iron-based dyes that could produce black colours. By the 16th century anyone with any pretense of status was seeking out black clothing, with it becoming ubiquitous for both the upper and merchant classes by the 17th century.
City-dwelling merchants and craftspeople (I like this term better than "middle class") would have access to commercially-available cloth (as well as tailors), and tended to buy the most costly fabric they could afford (which is in fact the origins of "sumptuary laws" restricting certain fibres and colours to certain classes; these were usually observed more in the breach, with being able to pay the fines being a source of pride). Those of the labouring classes that lived in the countryside might also have had some access to commercially-produced cloth, but also homespun-and-dyed cloth. For obvious reasons, therefore, the dye processes would need to be simple and straightforward using locally-available dyestuffs, with the very poorest likely forgoing dyeing altogether.