Um, that's not exactly the best way of structuring an essay...
Agreed.
Personally, I loathe introductory and conclusion paragraphs, but some form of that is needed so it’s hard to get away from those blights.
And of course, an essay should never contain anything resembling the phrase "I think this" unless it is along the lines of a This I Believe essay. A good essay should be so well reasoned and supported by evidence that it isn't "what you think" about a topic but what your know, as it were.
Trust me, instructors can sense fluff with great ease. I've graded such essays before and they're physically painful to read... unless they are so horrible that they're actually funny. But then I usually am laughing so hard at how bad they are that I hurt myself. So yeah, just physically painful all round.
Generally, as long as the teacher has any hope or motivation left, you're better turning in something under the minimum requirement than to turn in fluff. It shows you have academic integrity. Fluff is just an insult.
Id, the fact that you were able to get an A in English with that approach is one of the reasons the current school systems are a disgrace to civilizations everywhere.