跑步 is a separable verb. As a simple example, if you wanted to write "We met yesterday", you would write: 我们昨天见了面。 见面 is also separable, and we would not write 我们昨天见面了。For more information, go to: https://resources.allsetlearning.com/chinese/grammar/Separable_verb

These are separable verbs (also called verb object phrases). You can typically identify them when the first character indicates an action and the second character indicates a noun. For example in 跑步, 跑 is actually the verb "to run" while 步 is a noun meaning "a step" as in a step in a process.

Modifiers should come after the verb word, and therefore are usually placed between the two characters that make up a separable word. These modifiers are typically auxiliary words like “着 (zhe), 了(le), 过(guò) and quantifiers as we see in this case with the quantifier “半个小时".

It is correct to say 我每天喜欢游泳 since there are no modifiers in your sentence. However if you wanted to say I swam for an hour then 我游了一个小时泳 would be correct. Note the verb modifiers come after the verb word which in this case is 游.

more on separable verbs: https://resources.allsetlearning.com/chinese/grammar/Separable_verb list of separable verbs: https://resources.allsetlearning.com/chinese/grammar/List_of_separable_verbs

This is also explained in duolingo's grammar section for this lesson.

I wonder the same.

Almost. "Everyday" is an adjective meaning "mundane". With "Every day" it should be accepted as correct whether it's at the beginning or end.

I say, "a half hour" in English. I think it should be accepted.

"For a half hour" is common usage in the United States. I answered the exact same way . It is correct. That is the way the English is spoken. I'm not changing my English. lol. I asked several different people about "Everyday" meaning boring or mundane, no one has every heard of that definition. I remember in the German course, "for a half hour" is used as English, and most Germanic languages have that usage as well.

half an hour, that's why

Yes, I was marked wrong for thirty minutes too. The app is in need of further development...

Because "everyday" is an adjective, e.g. "an everyday meal".

I agree. I was marked incorrect for using jog also.

Really? I was taught that it is "an" hour, because the "h" is silent, so it actually sounds like the word starts with a vowel. Similarly, you don't say "an" before words such as "unanimous", because although the first letter is a vowel it sounds like a consonant. But I'm not a native speaker so maybe that's wrong.