If my wife had our baby in January 2022 why am I not able to claim her as my dependent if she had no income the whole year?

[xmasbaby0]

You cannot claim a spouse as a dependent.  File a joint return.  You can claim your baby as a dependent on the joint return.

Married Filing Jointly is usually better, even if one spouse had little or no income. When you file a joint return, you and your spouse will get the married filing jointly standard deduction of $25,900 (+$1400 for each spouse 65 or older)  You are eligible for more credits including education credits, earned income credit, child and dependent care credit, and a larger income limit to receive the child tax credit. 

[Texas Roger]

When claiming the baby as a dependent, you should indicate that the baby lived with you the whole year. That is the right answer for a child born during the year.