Fifth day, December 5th

Initially let’s check Wikipedia page about famous people bourned on December, 5th and find the most known celebrities. Probably the most famous person from this list is Walter Elias Disney.

Studying the article about him, find the link to the first popular character created by him.

The Wikipedia article about Mickey Mouse cocntains the original name of the character

His original name was Mortimer. Check the answer and it is correct:

On the same page there is information about Walt Disney’s disappointing visit to Charles Mintz in February 1928.

Searching the info about negotiations between Disney and Mintz we get the link to the Disney Fandom Wiki

On the Fandom Wiki page Mintz mentioned in the Business section. And we find the date of the Disney’s trip from New York when he came up with the idea of a new character: 1928 March, 13th

On the wikipedia page about Mickey Mouse we see the character name, that was replaced by Mickey Mouse:

Follow the link to the Oswald the Lucky Rabbit page and see that the first appearance of this character was in the Trolley Troubles animated film

And the final answer is also correct

Used tools and services:

• Wikipedia
• Google Text Search