The Duolingo Hebrew course teaches modern Hebrew not Biblical Hebrew. Biblical Hebrew or classical Hebrew is similar but not the same to Modern Hebrew. The following are posts and archives about it. I do not plan on making individual posts for most of these as Duolingo doesn't teach it, but you are welcome to link to these or make archive posts with the links. Just remember to credit the author in your post.
Biblical vs Modern Hebrew - letter B - bet
Duolingo Hebrew - Will I be able to read biblical scriptures?
Biblical and Modern Hebrew Future Tense?!
How is learning Hebrew on Duolingo compare to learning Biblical Hebrew?
Biblical Hebrew Vowel Reduction
Will learning Modern Hebrew help me understand Biblical Hebrew?
For those asking about Modern-Biblical Hebrew Intelligibility
Biblical Hebrew syllable accentuation, and stress.
learning biblical Hebrew and stopped by the modern on duolingo
Biblical Hebrew resources
L1 
Advanced beginner