Humans aren't as bad as you think
Firstly, humans gets +1 to all stats, in the PHB (pg. 31):
Ability Score Increase. Your ability scores each increase by 1.
This means, as @SeriousBri pointed out in a comment (now deleted), they can get higher starting stats when using the point buy system. But even with rolling for stats, if you end up with a bunch of odd numbers, this can increase all of the modifiers by one.
(To quote a player at an RPG club I go to, after rolling either mostly or entirely odd numbers: "Well... looks like I'll be going human!")
Secondly, the variant human rules (which I believe is AL-legal, as far as RAW goes). They get +1 to two stats, plus a free skill proficiency, plus a feat. This last point makes them very strong (depending on what feat you're going for).
From the PHB again, page 31:
Variant Human
If your campaign uses the optional feat rules from the Player’s Handbook, your Dungeon Master might allow these variant traits, all of which replace the human’s Ability Score Increase trait.
Ability Score Increase. Two different ability scores of your choice increase by 1.
Skills. You gain proficiency in one skill of your choice.
Feat. You gain one feat of your choice.
As an example, making a Barbarian or Paladin or something who uses a great weapon, you can pick the Great Weapon Master feat, which allows a second attack (as a bonus action) if you crit or kill something. This is essentially Extra Attack at level 1, which is very strong.
Furthermore, it's possible for a human using the variant rules to have a 20 in a stat at level 1. As an example, elves get +2 to Dexterity, so if they roll an 18, they can have a 20 in Dexterity at level 1. However, recently a player in a game I'm playing in rolled an 18 as a human wizard, put that in Intelligence, used one of their "+1 to any two stats" to make that a 19, then took the Linguist feat (which, among other things, gives +1 to Intelligence) to increase that to 20.
Ok, so they don't have darkvision, but neither do Dragonborn or Halflings.
Best Answer
Well, Wizards released an entire web enhancement devoted to cats as an April Fools article, which has a lot of cool options for cats. It does have at least one “playable” cat (Cheshire Cat, to be exact), but it’s not really a very playable option because it has LA +3. If it lost the DR, toned down the ability score bonuses a bit, it could possibly pass as a more playable LA +1.
The more typical answer to the desire to play as a cat is to use the tibbit race from Dragon Compendium. These shapeshifters can take on the form of a housecat, and are an LA +0 race (i.e. in line with the regular races). In their regular form, they are Small, have −2 Strength but +2 Dexterity, and Darkvision out to 60 ft.
Catfolk are in Races of the Wild, but they’re fairly disappointing. They have LA +1, and get very little to show for it, sadly.
Shifters from Eberron Campaign Setting or Races of Eberron are quasi-lycanthropes that can “shift” or become more bestial, with fangs or claws or what have you. Could be somewhat feline, but mostly it’s just humanoid with claws etc. They are LA +0, but tend to be fairly underwhelming even for an LA +0 race: while shifting, they’re pretty typical, but that means when they’re not shifting, they’re sub-par.
Both tibbits and catfolk can probably qualify as “feline” for the purposes of the feats and similar in the Fabulous Cats! article. Shifters could if you let them, I suppose.
As for homebrew, bhu has a fair amount of kitty-related homebrew, and he’s a fairly noted ’brewer. I haven’t personally read any of his cat stuff, though.