In regards to lore research I often use Wowpedia. It is often a good source to research things new and old, especially if you go into knowing what you’re looking for. Reading about notable characters, lore on the playable classes, their cultural variants or classes from the table top game can also help in providing inspiration for characters. There may be other good sources but I know of few that provide decent narrative info.
Here are links to the general lore pages on the races you mentioned:
https://wowpedia.fandom.com/wiki/Human
https://wowpedia.fandom.com/wiki/Night_elf
I’m also gonna link a thread that archives roleplaying guides. Considering what’s there I’m certain you can find something helpful. Be aware that some of the guides there are rather old by now and might contain outdated info:
Compendium of Roleplay Guides [WIP] - Wyrmrest Accord - World of Warcraft Forums (blizzard.com)