The Lords are a mix of:

* Inherited peers who were supposed to be abolished or at least phased out but then weren't either, just statistically they'll tend to be older and have also inherited riches so while a few are knowledgeable and add value most aren't even decorative. Some of these are just a drain on the purse, they show up to collect "expenses" but don't actually do anything whatsoever. But others insist on having their say even if they nothing to offer.

* Politicians sent there. No better than they were when (or if, some had previously been in high ranking unelected positions) elected. Some of these serve as Ministers. Unlike the US the British cabinet must be selected from Parliament, all the Great Offices (most important) must by tradition comes from the Commons and thus elected MPs. But it's normal (and when your talent pool is a bit empty necessary) to have a bunch of Cabinet Ministers from the Lords. You can deliberately "elevate" people there because you want them for this purpose but as it's a lifetime deal they are still there until they die. The alternative, if someone seems electable, is to "parachute them in" to replace a retiring or dead MP from your party in a by-election, but this is a less certain way and usually much slower.

* Rich people who thought this sounded interesting. In principle you can't buy a place in the Lords. In practice if you are rich enough it's definitely possible though you may look very desperate in the process, particularly if you're in such a hurry that you must be lobby different groups as power shifts from one year to the next.

* Do Gooders. These people at least didn't really set out to be in the Lords and thus could be the voice of the ordinary person. Except they tend to be pretty exceptional - for example the 1980s children's TV presenter Floella Benjamin was made a Baroness, but that's after not only being probably one of the few black women lots of very white children in England saw (on TV) from one week to the next in their childhood but also a lifetime of charitable work.

The best of the Lords are when some expert (say, a person who worked as a General Practitioner seeing NHS patients for four decades before arriving in the Lords) tells the rest of the Lords how things are, and they realise they've just been schooled and vote accordingly. Lords are not required to have a party affiliation (technically neither are the Commons but you're basically useless without one there). So-called "Cross benchers" are common, and relatively powerful.

* A bunch of actual Bishops. They probably shouldn't be there these days, and they mostly stay out of the way because they know that too, but for now they still are. When the Lords was created it made sense to have Bishops. There also used to be Judges, but those are now across the road in the independent Supreme Court.

The Lords often end up doing a lot of the "good" stuff you see the Senate doing. Dragging powerful people in to explain themselves on camera; actually reading the paperwork that the Commons was in too much of a hurry to get out the door and noticing all the horrible technical mistakes. "Did you mean to miss six year olds out for some reason? Or is this age mismatch between paragraphs 16b and 16c a typo?". That sort of thing.