Biblical 'kinds' would be any such species or varieties within a division that allows for cross fertility within its limits. The boundary would be drawn at the point where fertilization ceases to occur. Has the unchangeable rule that 'kinds' can not cross a biological principle been successfully challenged? So each basic group is apart from other 'kinds'. Sterility continues to be the determining factor as to what makes up a 'kind'.
Estimates are that Noah would have needed 43 kinds of mammals, 74 kinds of bird life and 10 kinds of reptiles to have the amount of variety we see today.
And what happened to the insects, pray tell?
In that case a kind is the same thing as a species. There are at least 12 million that we know about. True, many of those are aquatic, so let's call it around 6 million. Two of each. So what you're telling me is that Noah was floating around in a big wooden box with more than 10 million animals? (That's applying your definition in reality.)
For example, there are around 350,000 species of beetle alone. How much room do you think Noah set aside for beetles, do you suppose?
If, on the other hand, we use your ludicrous numbers...well let's do mammals first. You're saying Noah brings 43 "kinds" whatever the heck that may be. We know about around 5400 different species of mammals. That means that Noah's 43 kinds evolved into 5400 species in the last 6000 years alone. So what you're saying is that new species evolve. In fact, they evolve very rapidly, so rapidly that you'd have around one new species of mammal every year. Is that what we observe? Have you noticed any new species of mammals evolving in the last ten years?
Which is it, do new species evolve, or don't they?
Now let's talk about fish. There are three environments for fish, and no fish can live in the other. (Not even taking temperature into account.) They are fresh, salt and brackish. Salt water fish cannot survive in fresh water, etc. So how do you think the fish survived the mythical flood?