Frankly, European culture might not even arise as per OTL. Europe already had major brushes with societal collapse during bitter winters. With far more trees throughout Indonesia and other areas, the climate may inch colder, which could lead to Europe not being able to develop the edge needed to colonize the world.
The issue with Negrito groups is that, in a sense, they were "black people's black people" to the Europeans, and thus were extremely discriminated against under colonial regimes and etc. We actually have very little grasp on the histories and identities of Negrito people to this day as well.
For one, Negritos are not one homogenous group. Thus, we can't simply say that they are a blanket group of people who lived in Asia before the arrival of groups like the Dravidians and Sino-Tibetans and more recognizable "asians" to today. If I had a dollar for every shattered memory of a group who lived in an area before a more recognizable population showed up, I could pay for college. And unfortunately,
as you can read in my mental breakdown here, most of these groups have had major parts slip from recollection. Unfortunately, once you start getting too deep down the rabbit hole trying to find more information, people start talking about cranium sizes and shit like that and all of your sources turn to Nazi horseshit about how the untermensch once ruled the world.
To try to give a more coherent answer: A lot of the small islands, along with New Zealand, are empty. As for the population of Indonesia, the Philippines, and other areas, you have... options. Lots of options. You could have
Dravidians,
several groups of Australian Aboriginals or
even more ancient Tasmanians,
Papuans who make up at least 23 language families,
Andamanese,
a few options for Negritos,
the seldom mentioned Orangs,
Austroasiantic peoples, or you could just full on make some shit up because trying to figure out native Oceanian language families is the kind of thing that gives linguists and anthropologists night terrors and like 99% of the time your guess is as good as theirs. These groups would be divided into small kingdoms, with the general trend of more ancient peoples being pushed into the hinterlands while newer people take more coastal areas. As time went on, a naval culture could emerge, especially if contact is established with India. My advice is to not play the guessing game of "ooo when did we reach
M E N T A L M O D E R N I T Y" because unfortunately that argument is rather tainted by folks who like to rag on how Australian Aboriginals are less evolved than "modern people." (Seriously, go to any Australian forum and type in "aboriginals" and take a shot every time you read something that makes you question humanity's future. You'll be blackout drunk in less time than it takes to watch an episode of the Big Bang Theory).
TL;DR: Most of the areas would be empty or filled with a diverse cast of peoples who only survive in small remnant populations to this day, and Aqua really needs to go to bed and stop angerposting on the internet.