You do realize that a "High Score" of 45,000 on a 10 minute game of Jungle Cruise will only get you 675 Credits at 1.5 while a "High Score" of 8000 on a 11 Minute game of Fireworks will get you 1,600 credits. (This being based on the high score list, not an average player's ability.)
If the developers intentions are that Fireworks is the main way to make credits then they are doing it right. However; if they want the games played equally they need to increase Jungle Cruise's credits.
While this is true for those earning 8,000 points in fireworks (which is only a small handful), those who earn 4,000 points in fireworks could still likely manage 37k+ in Jungle Cruise consistently. Jungle Cruise is better for them.
Basically, it seems that the range of scores people get in Jungle Cruise is relatively small, like 35k-45k. So credits, though lower than doing perfectly in fireworks, are nearly equal for everybody. I think this is fine, since it'll stop all the complainers who yell about how they deserve more credits for their 1500 points in fireworks. But those who are still doing really well at fireworks and putting time/work into that can earn more credits.