It may go against established tropes, but more contemporary role-playing games allow for more freedom in character concepts by lifting these restrictions. For example, dwarf magic-users might be possible but instead a rarity due to cultural taboos. This gives outlier PCs a good story hook for why they defied societal expectations and serves as a potential world-building tool.
Regarding humans, I suggest granting PCs belonging to this race a +2 bonus in the ability score of their choice to a maximum value of 18. That way, they’re still an attractive option to pick even with the lack of being able to detect secret doors or see in the dark. I also recommend capping the max saving throw bonus one can receive from a race and class combination (such as dwarves and drow) to no more than +4 to avoid too large a change in probability.
In Swords & Wizardry, the dwarf and elf have three unique racial traits each, with half-elves and halflings two. Overall most races in OSR games have three iconic traits when they’re not classes, so in the creation of new races or adaption of existing ones you should think of three abilities which best exemplify them.
Drow are the descendants of elves who journeyed deep underground after being exiled from the old kingdoms. The harshness of underground life makes them more warlike and socially darwinist than their surface kin, and they’re quite fond using vermin such as giant spiders as pets and beasts of burden.
Traits: Drow are trained in the ability to use poison without error akin to the assassin class. They have darkvision to a range of 120 feet, and a +4 bonus on saving throws vs. damaging spells.
Gnomes are short folk who live in hilly burrows and forested mounds. It is believed that they have strong ties to the fey, and the ones who take up magical arts prefer spells of the subtler variety.
Traits: Gnomes gain a +4 bonus on saving throws vs. illusion spells and effects which would otherwise fool their minds or senses. They can also see in the dark up to 60 feet. Finally, gnomes have a 4 in 6 chance of understanding the purpose or workings of advanced technological and alchemical devices. “Advanced technology” tends to cover items of a post-Renaissance nature or things uncommon in typical fantasy settings, such as clockwork, gunpowder, steampower, and the like.
Pixies are tiny winged fey (around 2’ tall on average) with a connection the forests of the world. They seem possessed by boundless energy, are fond of entertainment of all sorts, and innately magical.
Traits: Pixies are tiny in stature and thus can have a maximum Strength score of 11 (any amount rolled over this is treated as an 11 result). They can fly at a speed of 30 feet, but must rest for 1 minute for every 3 minutes they spend flying. Pixies can also sprinkle dust from their wings on weapons and ammunition once per day, which can inflict the effects of a charm person or sleep spell on a struck target with an effective Magic-User level equal to the pixie’s total class levels.
Magocracies often make dangerous pacts with otherworldly entities as a measure of preserving power. Some of these pacts involve tainting unborn children with the spark of eldritch forces which manifest as demonic-like qualities in life. Tieflings are the descendents of these cursed children, feared as demonspawn and changelings in some lands, revered by fiendish sorcerers and cultists for their potent bloodline.
Traits: Tieflings gain a +4 bonus on saving throws vs. effects of an elemental nature, such as fire, ice, electricity, earth, and air. They have darkvision to a range of 60 feet, and can cast darkness 15 foot radius once per day as an innate ability with an effective magic-user level equal to their total class levels.
Vampires are undead creatures who must subsist on the blood of the living. They are quite powerful as undead, retaining their intelligence and free will and capable of performing terrible abilities even if not a spellcaster.
Traits: Vampires do not need to eat, sleep, or breathe as undead beings, but they must subsist on a pint of blood every week or suffer the effects of starvation. They have a natural bite attack which deals 1d4 damage on a hit; a vampire can suck the blood out of a helpless or willing target healing 1 hit point of damage for every 2 points dealt via a bite. Vampires can also take the form of a bat or wolf as per polymorph self with an effective Magic-User level equal to their total class levels, although they’re still treated as undead in this form as well.
Note: In typical OSR games, vampires come with a variety of powers and weaknesses beyond the template presented here. It is assumed that the vampire “race” presented above is a fledgling barely coming into their powers; as a result they still possess enough qualities from their old life to not worry about sunlight, garlic, and the like.
If this doesn’t seem authentic, you can introduce this rule for vampire weaknesses: vampires in prolonged contact with hostile elements take 1d4 points of damage per round of contact. Vampires reduced to 0 hit points from this type of damage crumble into dust.