Does the verse: {And of knowledge, you have been given but little} include the past and the present, and what knowledge is meant by it, and does that include all sciences?

The verb here is in the past tense and refers to what has preceded, while those who came later have little knowledge. This encompasses all sciences and branches of knowledge, for humans have only been exposed to a small fraction of them. As narrated in Sahih Al-Bukhari from Ibn Abbas, in the story of Moses and Al-Khidr (peace be upon them), Al-Khidr said to Moses: "My knowledge and your knowledge, compared to Allah's knowledge, are like the amount of water a bird takes from the sea with its beak."