There won't be any challenges. Respawn said that when Season 1 released. There may be challenges in a future Battle Pass, but not in Season 1.
New Weapons? I only know about the L-Star... and that will be only an airdrop weapon... so it's really rare.
A new character is the least they can release. When season 1 is finished we have 1 regular new weapon, 1 rare weapon, 2 new weapons, 0 challenges, 0 changes to the map, possibly 0 exciting new skins or calling cards, communication reduced to a minimum... and all in all a extremely underwhelming Battle Pass.
Of a game that just released. I challenge you to find any game with more added content in 2 months.
L star is coming but also probably a new grenade\gadget. Other fully rendered weapons have been found, but we do not know if they arriving soon ( they are ready though)
We have Watson coming and probably a map modification ( the Arena is going to be an actual arena)