God actually cares a lot about animals. He mentioned one of the reasons He wanted to save the Ninevites was also for the animals: "Should I not have compassion on Nineveh, the great city in which there are more than 120,000 persons who do not know the difference between their right and left hand, as well as many animals?" (Jonah 4:11)
God gave people dominion over animals and the whole earth, but when humans sinned, animals suffered too.
Are animals completely innocent? Not really.
Even dogs know shame. When they make a mess and their owner scolds them, they know they shouldn't have done what they did and they cover their faces.
The Bible says that the snake which let Satan enter was partly responsible for the fall of mankind:
“The Lord God said to the serpent,
‘Because you have done this,
Cursed are you more than all cattle,
And more than every beast of the field;
On your belly you will go,
And dust you will eat
All the days of your life…'” (Genesis 3:14)
Snakes do eat dust. They sample bits of dust on their forked tongues and present the dust to the sensory organs inside their mouths (Jacobson’s organ). In this way, snakes sample and smell dust. They quickly clean their tongues each time in order to repeat the process again and again. (Source: https://creation.com/snakes-do-eat-dust)
"Who knows that the breath of man ascends upward and the breath of the beast descends downward to the earth?" (Ecclesiastes 3:21)
From this verse we can see that it is not true that all people go to heaven. Perhaps it is also not true that all animals cease to exist after they die. Perhaps some of them do go to heaven.
"O Lord, You preserve man and beast." (Psalm 36:6)
The God of the earth will do what is right.