It's a mix of different textures I found online, some I made myself and some I got from modern minecraft.
I've tried to make it a nice and soft vanilla vibe with lagoon type water and smoother textures. I think you need optifine to see the water though. It might not look that different on here but there is a really quite noticeable difference in game. I haven't really changed the items tho so this terrain.png should be all you need:
I changed the netherrack texture because it was annoying me. It's now much smoother and flatter. I'm not sure I like it though. It's a simple retexture of stone. Here are some screenshots, the nether still looks good:
