A story is made up beats. In a satisfying story, these beats are intimately connected, each leading to the next.

Ratatouille we meet Remi, a rat who loves food and idolizes a chef.
His father believes he should just eat garbage and focus on survival.

• One day Remi finds a rare mushroom and fine cheese that he wants to prepare using saffron.
• Therefore he sneaks into the kitchen of a sleeping old woman
  
• but he distracted by the television where he learns his favourite chef is dead
• therefore he makes a surprised squeak 
• therefore the old woman awakens and, seeing rats in her home, grabs her shotgun and starts shooting
• therefore Remi and his friend run around the kitchen and fall onto the chandelier
• therefore the old woman shoots the chandelier
  
• but this collapses the ceiling, revealing the hundreds of rats living in the ceiling.
  
• therefore the rats scatter and evacuate to the river
• but Remi returns to the kitchen to take the cookbook
• therefore he is late to the river where his family are already floating away toward the sewer. Remi doesn’t have a boat!
  
• but Remi is able to use the cookbook as a boat to catch up to his family
  
• but the old woman shoots at him and he is left behind
• therefore Remi is alone, separated from his family and carried away by the rushing water

The characters have conflicting desires and their actions stem naturally from those desires. The characters are in stark contrast to each other and their desires tap into deeper themes about life: survival vs. beauty. Is it worth dying for something beautiful? Is life worth living with nothing beautiful?

This whole intro scene is the inciting incident that kicks off the story.

But / Therefore

“We found out this really simple rule that maybe you guys heard
before, but it took us a long time to learn it. We can take these beats,
which are basically the beats of your outline, and if the words ‘and
then’ belong between those beats, you’re fucked—basically. You’ve got
something pretty boring. What should happen between every beat that
you’ve written down, is either the word ‘therefore’ or ‘but’. So you
come up with an idea and write ‘and this happens…and then this happens…’
no, no, no. It should be ‘this happens and therefore, this happens’.
‘But, this happens, therefore, this happens….’”

The plot advances due to characters, not the writer.