What has happened with you is unfortunate. Sudden loss of job is as good as meeting some accident. Accidents always leave a person bruised or scarred. The event must have come as a body blow to your career.
Few questions arise from your post. First one is about your reporting authority. If you are from HR, then why do you report to Line Manager? Is authority of line manager over and above the HR Manager?
Secondly, when line manager objected for having browsing HR related website, how did you convince him? Is browsing website during duty time prohibited? Secondly, did you tell him that setting up department may require collecting information from the public domain. If you do that, you will not have to reinvent the wheel
Now let us look at the opposite side. Possibly, your line manager might have very strong intellectual modesty. He could be valuing originality and considering that the "copy and paste" job is plain plagiarism. A person who does plagiarism lacks self-esteem. He might be holding these views. Thanks to Google, the current generation has been converted into copycats or download masters. He could be detesting that. However, it may be true or may not be true.
In hindsight let us look at the incident. If what I have stated in the above paragraph is not true then it appears that your line manager was upset on you as such and browsing website could to be a ploy to remove you. Otherwise, this is a minor misconduct and does not merit removal from the job as such. Partially I attribute the outcome of the incident to your communication skills also. The way you have written your post shows you need to improve your communication skills. Lastly, did you try to assess the nature of the line manager? Is he the one who calls shots in the company? If yes, then it would have been pertinent to take permission for browsing HR-related websites.
Anyway do not lose your heart. Possibly you are destined to get a better job. Therefore, start searching for a new job vigorously. In your CV, do not include your 28-day tenure. Otherwise, it could create one more problem for you. For further queries, feel free to contact me
All the best! Dinesh Divekar 18th June 2017 From India, Bangalore