I know that we usually write at the start of our answer this sentence. "These are the types or factors of something". Could we write this sentence at the end of the answer. ?Or should we write "these were the factors of ...."at the end of the sentence??
In written English, an ending in the past tense would normally mean that the writing is about events in the past: "These were the causes of the French revolution". More usually, we write in present tense for things which expect to still be the case: "And so, in summary, these are factors to be taken into account."
(However, scientific articles in journals are almost entirely in the past tense: X was done, X was measured, X was a factor in the process etc.)
The past tense is more common in endings in spoken English: such as in a conversation or presentation, where it is the telling which is in the (immediately recent) past: "These were the things I wanted to tell you".